Title: Theory / Important / CS / Programming / Python / glossary

Name: >>>
Definition: The default Python prompt of the interactive shell. Often seen for code examples which can be executed interactively in the interpreter.
Context: Python

Name: ...
Definition: The default Python prompt of the interactive shell when entering code for an indented code block or within a pair of matching left and right delimiters (parentheses, square brackets or curly braces).
Context: python

Name: 2to3
Definition: A tool that tries to convert Python 2.x code to Python 3.x code by handling most of the incompatibilities which can be detected by parsing the source and traversing the parse tree.
Context: Python
Extra: 2to3 is available in the standard library as lib2to3; a standalone entry point is provided as Tools/scripts/2to3. See 2to3 - Automated Python 2 to 3 code translation.

Name: abstract base class
Definition: Abstract base classes complement duck-typing by providing a way to define interfaces when other techniques like hasattr() would be clumsy or subtly wrong (for example with magic methods). ABCs introduce virtual subclasses, which are classes that don't inherit from a class but are still recognized by isinstance() and issubclass(); see the abc module documentation. Python comes with many built-in ABCs for data structures (in the collections.abc module), numbers (in the numbers module), streams (in the io module), import finders and loaders (in the importlib.abc module). You can create your own ABCs with the abc module.
Context: Python

Name: argument
Definition: A value passed to a function (or method) when calling the
function. There are two kinds of argument:
- keyword argument: an argument preceded by an identifier (e.g.
name=) in a function call or passed as a value in a dictionary
preceded by **. For example, 3 and 5 are both keyword
arguments in the following calls to complex():
complex(real=3, imag=5)
complex(**{'real': 3, 'imag': 5})
- positional argument: an argument that is not a keyword argument.
Positional arguments can appear at the beginning of an argument list
and/or be passed as elements of an iterable preceded by *.
For example, 3 and 5 are both positional arguments in the
following calls:
complex(3, 5)
complex(*(3, 5))
Arguments are assigned to the named local variables in a function body.
See the Calls section for the rules governing this assignment.
Syntactically, any expression can be used to represent an argument; the
evaluated value is assigned to the local variable.
See also the parameter glossary entry, the FAQ question on
the difference between arguments and parameters, and PEP 362.
Context: Python

Name: attribute
Definition: A value associated with an object which is referenced by name using dotted expressions.
Context: Python
Extra: For example, if an object o has an attribute a it would be referenced as o.a.

Name: Benevolent Dictator For Life
Definition: Guido van Rossum, Python's creator.
Context: Python
Abbreviation: BDFL

Name: binary file
Definition: A file object able to read and write bytes-like objects.
Context: Python

Name: bytes-like object
Definition: An object that supports the Buffer Protocol, like bytes, bytearray or memoryview. Bytes-like objects can be used for various operations that expect binary data, such as compression, saving to a binary file or sending over a socket.
Some operations need the binary data to be mutable, in which case not all bytes-like objects can apply.
Context: Python

Name: bytecode
Definition: Python source code is compiled into bytecode, the internal representation of a Python program in the CPython interpreter. The bytecode is also cached in .pyc and .pyo files so that executing the same file is faster the second time (recompilation from source to bytecode can be avoided). This “intermediate language” is said to run on a virtual machine that executes the machine code corresponding to each bytecode. Do note that bytecodes are not expected to work between different Python virtual machines, nor to be stable between Python releases.
A list of bytecode instructions can be found in the documentation for the dis module.
Context: Python

Name: class
Definition: A template for creating user-defined objects. Their definitions normally contain method definitions which operate on instances of it.
Context: Python
Name2: new-style class (not used anymore that there is no old-style class)
Extra: Old name for the flavor of classes now used for all class objects. In earlier Python versions, only new-style classes could use Python's newer, versatile features like __slots__, descriptors, properties, __getattribute__(), class methods, and static methods.

Name: coercion
Definition: The implicit conversion of an instance of one type to another during an operation which involves two arguments of the same type. For example, int(3.15) converts the floating point number to the integer 3, but in 3+4.5, each argument is of a different type (one int, one float), and both must be converted to the same type before they can be added or it will raise a TypeError. Without coercion, all arguments of even compatible types would have to be normalized to the same value by the programmer, e.g., float(3)+4.5 rather than just 3+4.5.
Context: Python

Name: complex number
Definition: An extension of the familiar real number system in which all numbers are expressed as a sum of a real part and an imaginary part.
Context: Python
Extra: Imaginary
numbers are real multiples of the imaginary unit (the square root of
-1), often written i in mathematics or j in
engineering. Python has built-in support for complex numbers, which are
written with this latter notation; the imaginary part is written with a
j suffix, e.g., 3+1j. To get access to complex equivalents of the math module, use cmath. Use of complex numbers is a fairly
advanced mathematical feature. If you're not aware of a need for them,
it's almost certain you can safely ignore them.

Name: context manager
Definition: An object which controls the environment seen in a with statement by defining __enter__() and __exit__() methods.
Context: Python
Extra: See PEP 343.

Name: decorator
Definition: A function returning another function, usually applied as a function transformation using the @wrapper syntax.
Context: Python
Example: Common examples are classmethod() and staticmethod().
Extra: The decorator syntax is merely syntactic sugar, the following two
function definitions are semantically equivalent:
def f(...):
    ...
f = staticmethod(f)
@staticmethod
def f(...):
    ...
The same concept exists for classes, but is less commonly used there. See
the documentation for function definitions and
class definitions for more about decorators.

Name: descriptor
Definition: Any object which defines the methods __get__(), __set__(), or __delete__(). When a class attribute is a descriptor, its special binding behavior is triggered upon attribute lookup. Normally, using a.b to get, set or delete an attribute looks up the object named b in the class dictionary for a, but if b is a descriptor, the respective descriptor method gets called. Understanding descriptors is a key to a deep understanding of Python because they are the basis for many features including functions, methods, properties, class methods, static methods, and reference to super classes
Context: Python
Extra: For more information about descriptors' methods, see Implementing Descriptors.

Name: dictionary
Definition: An associative array, where arbitrary keys are mapped to values. The keys can be any object with __hash__() and __eq__() methods.
Context: Python
Extra: Called a hash in Perl.

Name: docstring
Definition: A string literal which appears as the first expression in a class, function or module. While ignored when the suite is executed, it is recognized by the compiler and put into the __doc__ attribute of the enclosing class, function or module. Since it is available via introspection, it is the canonical place for documentation of the object.
Context: Python

Name: duck-typing
Definition: A programming style which does not look at an object's type to determine if it has the right interface; instead, the method or attribute is simply called or used.
Context: Python
Extra: By emphasizing interfaces rather than specific types,
well-designed code improves its flexibility by allowing polymorphic
substitution. Duck-typing avoids tests using type() or
isinstance(). (Note, however, that duck-typing can be complemented
with abstract base classes.) Instead, it
typically employs hasattr() tests or EAFP programming.
Etymology: “If it looks like a duck and quacks like a duck, it must be a duck.”

Name: Easier to ask for forgiveness than permission
Definition: This common Python coding style assumes the existence of valid keys or attributes and catches exceptions if the assumption proves false. This clean and fast style is characterized by the presence of many try and except statements. The technique contrasts with the LBYL style common to many other languages such as C.
Context: Python
Abbreviation: EAFP

Name: expression
Definition: A piece of syntax which can be evaluated to some value.
Context: Python
Extra: In contrast to many other languages, not all language constructs are expressions. There are also statements which cannot be used as expressions, such as if.
Counterexample: Assignments

Name: extension module
Definition: A module written in C or C++, using Python's C API to interact with the core and with user code.
Context: Python

Name: file object
Definition: An object exposing a file-oriented API (with methods such as read() or write()) to an underlying resource. Depending on the way it was created, it can mediate access to a real on-disk file or to another type of storage or communication device (for example standard input/output, in-memory buffers, sockets, pipes, etc.). File objects are also called file-like objects or streams.
Context: Python
Name2: file-like object
Extra: There are actually three categories of file objects: raw binary files, buffered binary files and text files. Their interfaces are defined in the io module. The canonical way to create a file object is by using the open() function.
Name3: I/O object

Name: finder
Definition: An object that tries to find the loader for a module. It must implement either a method named find_loader() or a method named find_module(). See PEP 302 and PEP 420 for details and importlib.abc.Finder for an abstract base class.
Context: Python

Name: floor division
Definition: Mathematical division that rounds down to nearest integer. The floor division operator is //. For example, the expression 11 // 4 evaluates to 2 in contrast to the 2.75 returned by float true division. Note that (-11) // 4 is -3 because that is -2.75 rounded downward. See PEP 238.
Context: Python

Name: function
Definition: A series of statements which returns some value to a caller. It can alsoo be passed zero or more arguments which may be used in the execution of the body. See also parameter, method, and the Function definitions section.
Context: Python

Name: function annotation
Definition: An arbitrary metadata value associated with a function parameter or return value. Its syntax is explained in section Function definitions. Annotations may be accessed via the __annotations__ special attribute of a function object.
Python itself does not assign any particular meaning to function annotations. They are intended to be interpreted by third-party libraries or tools. See PEP 3107, which describes some of their potential uses.
Context: Python

Name: garbage collection
Definition: The process of freeing memory when it is not used anymore. Python performs it via reference counting and a cyclic garbage collector that is able to detect and break reference cycles.
Context: Python

Name: generator
Definition: A function which returns an iterator. It looks like a normal function except that it contains yield statements for producing a series a values usable in a for-loop or that can be retrieved one at a time with the next() function. Each yield temporarily suspends processing, remembering the location execution state (including local variables and pending try-statements). When the generator resumes, it picks-up where it left-off (in contrast to functions which start fresh on every invocation).
Context: Python

Name: generator expression
Definition: An expression that returns an iterator. It looks like a normal expression followed by a for expression defining a loop variable, range, and an optional if expression. The combined expression generates values for an enclosing function:
>>> sum(i*i for i in range(10))         # sum of squares 0, 1, 4, ... 81
285
Context: Python

Name: GIL
Definition: See global interpreter lock.
Context: Python

Name: global interpreter lock
Definition: The mechanism used by the CPython interpreter to assure that only one thread executes Python bytecode at a time.
Context: Python
Abbreviation: GIL
Extra: This simplifies the CPython implementation by making the object model (including critical built-in types such as dict) implicitly safe against concurrent access. Locking the entire interpreter makes it easier for the interpreter to be multi-threaded, at the expense of much of the parallelism afforded by multi-processor machines.
However, some extension modules, either standard or third-party, are designed so as to release the GIL when doing computationally-intensive tasks such as compression or hashing. Also, the GIL is always released
when doing I/O.
Past efforts to create a “free-threaded” interpreter (one which locks shared data at a much finer granularity) have not been successful because performance suffered in the common single-processor case. It is believed that overcoming this performance issue would make the implementation much more complicated and therefore costlier to maintain.

Name: hashable
Definition: An object which has a hash value which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() method). if they compare equal must have the same hash value.
Context: Python
Extra: Hashability makes an object usable as a dictionary key and a set member, because these data structures use the hash value internally.
All of Python's immutable built-in objects are hashable, while no mutable containers (such as lists or dictionaries) are. Objects which are instances of user-defined classes are hashable by default; they all compare unequal (except with themselves), and their hash value is their id()

Name: Integrated Development Environment.
Definition: A basic editor and interpreter environment which ships with the standard distribution of Python.
Context: Python
Abbreviation: IDLE

Name: An immutable object
Definition: An object with a fixed value.
Context: Python
Example: numbers, strings and tuples
Extra: A new object has to be created if a different value has to be stored. They play an important role in places where a constant hash value is needed, for example as a key in a dictionary.

Name: Import path
Definition: A list of locations (or path entries) that are searched by the path based finder for modules to import.
Context: Python
Extra: During import, this list of locations usually comes from sys.path, but for subpackages it may also come from the parent package's __path__ attribute.

Name: Importing
Definition: The process by which Python code in one module is made available to Python code in another module.
Context: Python

Name: importer
Definition: An object that both finds and loads a module; both a finder and loader object.
Context: Python

Name: interactive
Definition: Python has an interactive interpreter which means you can enter statements and expressions at the interpreter prompt, immediately execute them and see their results. Just launch python with no arguments (possibly by selecting it from your computer's main menu). It is a very powerful way to test out new ideas or inspect modules and packages (remember help(x)).
Context: Python

Name: Interpreted
Definition: Python is an interpreted language, as opposed to a compiled one, though the distinction can be blurry because of the presence of the bytecode compiler. This means that source files can be run directly without explicitly creating an executable which is then run. Interpreted languages typically have a shorter development/debug cycle than compiled ones, though their programs generally also run more slowly. See also interactive.
Context: Python

Name: Iterable
Definition: An object capable of returning its members one at a time.
Context: Python
Example: all sequence types (such as list, str, and tuple)
Example2: some non-sequence types like dict, file objects
Extra: When an iterable object is passed as an argument to the built-in function iter(), it returns an iterator for the object. This iterator is good for one pass over the set of values. When using iterables, it is usually not necessary to call iter() or deal with iterator objects yourself. The for statement does that automatically for you, creating a temporary unnamed variable to hold the iterator for the duration of the loop. See also iterator, sequence, and generator.
Example3: objects of any classes you define with an __iter__() or __getitem__() method

Name: iterator
Definition: An object representing a stream of data. Repeated calls to the iterator's __next__() method (or passing it to the built-in function next()) return successive items in the stream. When no more data are available a StopIteration exception is raised instead. At this point, the iterator object is exhausted and any further calls to its __next__() method just raise StopIteration again. Iterators are required to have an __iter__() method that returns the iterator object itself so every iterator is also iterable and may be used in most places where other iterables are accepted. One notable exception is code which attempts multiple iteration passes. A container object (such as a list) produces a fresh new iterator each time you pass it to the iter() function or use it in a for loop. Attempting this with an iterator will just return the same exhausted iterator object used in the previous iteration pass, making it appear like an empty container.
More information can be found in Iterator Types.
Context: Python

Name: key function
Definition: A callable that returns a value used for sorting or ordering.
Context: Python
Name2: Collation function
Extra: For example, locale.strxfrm() is used to produce a sort key that is aware of locale specific sort
conventions.
A number of tools in Python accept key functions to control how elements
are ordered or grouped. They include min(), max(),
sorted(), list.sort(), heapq.nsmallest(),
heapq.nlargest(), and itertools.groupby().
There are several ways to create a key function. For example. the
str.lower() method can serve as a key function for case insensitive
sorts. Alternatively, an ad-hoc key function can be built from a
lambda expression such as lambda r: (r[0], r[2]). Also,
the operator module provides three key function constructors:
attrgetter(), itemgetter(), and
methodcaller(). See the Sorting HOW TO for examples of how to create and use key functions.

Name: keyword argument
Definition: See argument.
Context: Python

Name: lambda
Definition: An anonymous inline function consisting of a single expression which is evaluated when the function is called. The syntax to create a lambda function is lambda [arguments]: expression
Context: Python

Name: Look before you leap.
Definition: This coding style explicitly tests for pre-conditions before making calls or lookups. This style contrasts with the EAFP approach and is characterized by the presence of many if statements.
Context: Python
Abbreviation: LBYL
Counterexample: In a multi-threaded environment, the LBYL approach can risk introducing a race condition between “the looking” and “the leaping”. For example, the code, if key in mapping: return mapping[key] can fail if another thread removes key from mapping after the test, but before the lookup.
This issue can be solved with locks or by using the EAFP approach.

Name: list
Definition: A built-in Python sequence.
Context: Python
Extra: Despite its name it is more akin to an array in other languages than to a linked list since access to elements are O(1).

Name: list comprehension
Definition: A compact way to process all or part of the elements in a sequence and return a list with the results. result = ['{:#04x}'.format(x) for x in range(256) if x % 2 == 0] generates a list of strings containing even hex numbers (0x..) in the range from 0 to 255. The if clause is optional. If omitted, all elements in range(256) are processed.
Context: Python

Name: loader
Definition: An object that loads a module.
Context: Python
Extra: It must define a method named load_module(). A loader is typically returned by a finder. See PEP 302 for details and importlib.abc.Loader for an abstract base class.

Name: mapping
Definition: A container object that supports arbitrary key lookups and implements the methods specified in the Mapping or MutableMapping abstract base classes. Examples include dict, collections.defaultdict, collections.OrderedDict and collections.Counter.
Context: Python

Name: meta path finder
Definition: A finder returned by a search of sys.meta_path. Meta path finders are related to, but different from path entry finders.
Context: Python

Name: Metaclass
Definition: The class of a class. Class definitions create a class name, a class dictionary, and a list of base classes. It is responsible for taking those three arguments and creating the class.
Context: Python
Extra: More information can be found in Customizing class creation.
Intuition: Most object oriented programming languages provide a default implementation. What makes Python special is that it is possible to create custom metaclasses. Most users never need this tool, but when the need arises, metaclasses can provide powerful, elegant solutions. They have been used for logging attribute access, adding thread-safety, tracking object creation, implementing singletons, and many other tasks.

Name: Method
Definition: A function which is defined inside a class body.
Context: Python
Extra: See function and nested scope.
If called as an attribute of an instance of that class, the method will get the instance object as its first argument (which is usually called self).

Name: method resolution order
Definition: The order in which base classes are searched for a member during lookup.
Context: Python
Extra: See The Python 2.3 Method Resolution Order.

Name: module
Definition: An object that serves as an organizational unit of Python code.
Page: https://docs.python.org/3/reference/import.html
Chapter: 3
Section: 2.
Context: Python
Extra: Modules have a namespace containing arbitrary Python objects. Modules are loaded into Python by the process of importing
Intuition: File in a file system

Name: MRO
Definition: See method resolution order.
Context: Python

Name: mutable
Definition: Objects that can change their value but keep their id().
Context: Python

Name: named tuple
Definition: Any tuple-like class whose indexable elements are also accessible using named attributes (for example, time.localtime() returns a tuple-like object where the year is accessible either with an index such as t[0] or with a named attribute like t.tm_year).
A named tuple can be a built-in type such as time.struct_time, or it can be created with a regular class definition. A full featured named tuple can also be created with the factory function collections.namedtuple(). The latter approach automatically provides extra features such as a self-documenting representation like Employee(name='jones', title='programmer').
Context: Python

Name: namespace
Definition: The place where a variable is stored.
Context: Python
Extra: Namespaces are implemented as dictionaries. There are the local, global and built-in namespaces as well as nested namespaces in objects (in methods). Namespaces support modularity by preventing naming conflicts. For instance, the functions builtins.open and os.open() are distinguished by their namespaces. Namespaces also aid readability and maintainability by making it clear which module implements a function. For instance, writing random.seed() or itertools.islice() makes it clear that those functions are implemented by the random and itertools modules, respectively.

Name: namespace package
Definition: A package which serves only as a container for subpackages.
Context: Python

Name: nested scope
Definition: The ability to refer to a variable in an enclosing definition.
Context: Python
Extra: For instance, a function defined inside another function can refer to variables in the outer function. Note that nested scopes by default work only for reference and not for assignment. Local variables both read and write in the innermost scope. Likewise, global variables read and write to the global namespace. The nonlocal allows writing to outer scopes.

Name: object
Definition: Any data with state (attributes or value) and defined behavior (methods).
Context: Python
Definition2: Also the ultimate base class of any new-style class.

Name: Parameter
Definition: positional-or-keyword: specifies an argument that can be passed either positionally or as a keyword argument. This is the default kind of parameter, for example foo and bar in the following:
def func(foo, bar=None): ...
Context: Python
Definition2: positional-only: specifies an argument that can be supplied only by position. Python has no syntax for defining positional-only parameters. However, some built-in functions have positional-only parameters (e.g. abs())
Conjdef: either
Definition3: keyword-only: specifies an argument that can be supplied only by keyword. Keyword-only parameters can be defined by including a single var-positional parameter or bare * in the parameter list of the function definition before them, for example kw_only1 and kw_only2 in the following:
def func(arg, *, kw_only1, kw_only2): ...
Extra: Parameters can specify both optional and required arguments, as well as
default values for some optional arguments.
See also the argument glossary entry, the FAQ question on
the difference between arguments and parameters, the inspect.Parameter class, the
Function definitions section, and PEP 362.
Definition4: var-positional: specifies that an arbitrary sequence of positional arguments can be provided (in  addition to any positional arguments already accepted by other  parameters). Such a parameter can be defined by prepending the parameter name with *, for example args in the following:
def func(*args, **kwargs): ...
Definition5: var-keyword: specifies that arbitrarily many keyword arguments can be provided (in addition to any keyword arguments already accepted by other parameters). Such a parameter can be defined by prepending the parameter name with **, for example kwargs in the example
above.
DefType: A named entity in a function (or method) definition that specifies an argument (or in some cases, arguments) that the function can accept.

Name: path entry
Definition: A single location on the import path which the path based finder consults to find modules for importing.
Context: Python

Name: path entry finder
Definition: A finder returned by a callable on sys.path_hooks (i.e. a path entry hook) which knows how to locate modules given a path entry.
Context: Python

Name: path entry hook
Definition: A callable on the sys.path_hook list which returns a path entry finder if it knows how to find modules on a specific path entry.
Context: Python

Name: path based finder
Definition: One of the default meta path finders which searches an import path for modules.
Context: Python

Name: portion
Definition: A set of files in a single directory (possibly stored in a zip file) that contribute to a namespace package, as defined in PEP 420.
Context: Python

Name: Positional argument
Definition: See argument.
Context: Python

Name: Provisional package
Definition: A package which has been deliberately excluded from the standard library's backwards compatibility guarantees.
While major changes to such packages are not expected, as long as they are marked provisional, backwards incompatible changes (up to and including removal of the package) may occur if deemed necessary by core developers. Such changes will not be made gratuitously – they will occur only if serious flaws are uncovered that were missed prior to the inclusion of the package.
Context: Python
Extra: See PEP 411 for more details.
Intuition: This process allows the standard library to continue to evolve over time, without locking in problematic design errors for extended periods of time.

Name: Python 3000
Definition: Nickname for the Python 3.x release line
Context: Python
Abbreviation: Py3k
Etymology: coined long ago when the release of version 3 was something in the distant future.

Name: Pythonic
Definition: An idea or piece of code which closely follows the most common idioms of the Python language, rather than implementing code using concepts common to other languages.
Context: Python
Example: A common idiom in Python is to loop over all elements of an iterable using a for statement. Many other languages don't have this type of construct, so people unfamiliar with Python sometimes use a numerical counter instead:
for i in range(len(food)):
 print(food[i])
As opposed to the cleaner, Pythonic method:
for piece in food:
 print(piece)
Applied to: Looping over a list

Name: Qualified name
Definition: A dotted name showing the “path” from a module's global scope to a class, function or method defined in that module, as defined in PEP 3155. For top-level functions and classes, it is the same as the object's name:
>>> class C:
...     class D:
...         def meth(self):
...             pass
...
>>> C.__qualname__
'C'
>>> C.D.__qualname__
'C.D'
>>> C.D.meth.__qualname__
'C.D.meth'
When used to refer to modules, the fully qualified name means the entire dotted path to the module, including any parent packages, e.g. email.mime.text:
>>> import email.mime.text
>>> email.mime.text.__name__
'email.mime.text'
Context: Python

Name: Reference count
Definition: The number of references to an object.
Context: Python
Extra: When the reference count of an object drops to zero, it is deallocated. Reference counting is generally not visible to Python code, but it is a key element of the CPython implementation. The sys module defines a getrefcount() function that programmers can call to return the reference count for a particular object.

Name: Regular package
Definition: A traditional package, such as a directory containing an __init__.py file.
Context: Python

Name: __slots__
Definition: A declaration inside a class that saves memory by pre-declaring space for instance attributes and eliminating instance dictionaries.
Context: Python
Extra: Though popular, the technique is somewhat tricky to get right and is best reserved for rare cases where there are large numbers of instances in a memory-critical application.

Name: sequence
Definition: An iterable which supports efficient element access using integer indices via the __getitem__() special method and defines a __len__() method that returns the length of the sequence.
Context: Python
Extra: Some built-in sequence types are list, str,
tuple, and bytes. Note that dict also
supports __getitem__() and __len__(), but is considered a
mapping rather than a sequence because the lookups use arbitrary
immutable keys rather than integers.
The collections.abc.Sequence abstract base class
defines a much richer interface that goes beyond just
__getitem__() and __len__(), adding count(),
index(), __contains__(), and
__reversed__(). Types that implement this expanded
interface can be registered explicitly using
register().

Name: slice
Definition: An object usually containing a portion of a sequence.
Context: Python
Extra: A slice is created using the subscript notation, [] with colons between numbers when several are given, such as in variable_name[1:3:5]. The bracket (subscript) notation uses slice objects internally.

Name: special method
Definition: A method that is called implicitly by Python to execute a certain operation on a type, such as addition.
Context: Python
Extra: Special methods are documented in Special method names.
Denoted by: names starting and ending with double underscores

Name: statement
Definition: an expression
Context: Python
Definition2: one of several constructs with a keyword, such as if, while or for.
Conjdef: either
DefType: Part of a suite (a “block” of code).

Name: struct sequence
Definition: A tuple with named elements.
Context: Python
Extra: Struct sequences expose an interface similar to named tuple in that elements can either be accessed either by index or as an attribute. However, they do not have any of the named tuple methods like _make() or _asdict(). Examples of struct sequences include sys.float_info and the return value of os.stat().

Name: text file
Definition: A file object able to read and write str objects.
Context: Python
Extra: Often, a text file actually accesses a byte-oriented datastream and handles the text encoding automatically.
See also
A binary file reads and write bytes objects.

Name: triple-quoted string
Definition: A string which is bound by three instances of either a quotation mark (”) or an apostrophe (‘). While they don't provide any functionality not available with single-quoted strings, they are useful for a number of reasons. They allow you to include unescaped single and double quotes within a string and they can span multiple lines without the use of the continuation character, making them especially useful when writing docstrings.
Context: Python

Name: type
Definition: The type of a Python object determines what kind of object it is; every object has a type. An object's type is accessible as its __class__ attribute or can be retrieved with type(obj).
Context: Python

Name: universal newlines
Definition: A manner of interpreting text streams in which all of the following are recognized as ending a line: the Unix end-of-line convention '\n', the Windows convention '\r\n', and the old Macintosh convention '\r'. See PEP 278 and PEP 3116, as well as str.splitlines() for an additional use.
Context: Python

Name: view
Definition: The objects returned from dict.keys(), dict.values(), and dict.items() are called dictionary views. They are lazy sequences that will see changes in the underlying dictionary. To force the dictionary view to become a full list use list(dictview). See Dictionary view objects.
Context: Python

Name: virtual machine
Definition: A computer defined entirely in software.
Context: Python
Extra: Python's virtual machine executes the bytecode emitted by the bytecode compiler.

Name: Zen of Python
Definition: Listing of Python design principles and philosophies that are helpful in understanding and using the language. The listing can be found by typing “import this” at the interactive prompt.
Context: Python