Editing Python (programming language) (section)

===Statements and control flow===
Python's [[statement (computer science)|statements]] include the following:
* The [[Assignment (computer science)|assignment]] statement, using a single equals sign <code>=</code>
* The <code>[[if-then-else|if]]</code> statement, which conditionally executes a block of code, along with <code>else</code> and <code>elif</code> (a contraction of <code>else if</code>)
* The <code>[[Foreach#Python|for]]</code> statement, which iterates over an ''iterable'' object, capturing each element to a local variable for use by the attached block
* The <code>[[While loop#Python|while]]</code> statement, which executes a block of code as long as its condition is true
* The <code>[[Exception handling syntax#Python|try]]</code> statement, which allows exceptions raised in its attached code block to be caught and handled by <code>except</code> clauses (or new syntax <code>except*</code> in Python 3.11 for exception groups<ref>{{Cite web |title=8. Errors and Exceptions – Python 3.12.0a0 documentation |url=https://docs.python.org/3.11/tutorial/errors.html |access-date=2022-05-09 |website=docs.python.org |archive-date=9 May 2022 |archive-url=https://web.archive.org/web/20220509145745/https://docs.python.org/3.11/tutorial/errors.html |url-status=live}}</ref>); the <code>try</code> statement also ensures that clean-up code in a <code>finally</code> block is always run regardless of how the block exits
* The <code>raise</code> statement, used to raise a specified exception or re-raise a caught exception
* The <code>class</code> statement, which executes a block of code and attaches its local namespace to a [[class (computer science)|class]], for use in object-oriented programming
* The <code>def</code> statement, which defines a [[function (computing)|function]] or [[method (computing)|method]]
* The <code>[[dispose pattern#Language constructs|with]]</code> statement, which encloses a code block within a context manager, allowing [[resource acquisition is initialization|resource-acquisition-is-initialization]] (RAII)-like behavior and replacing a common try/finally idiom<ref>{{cite web|url=https://www.python.org/download/releases/2.5/highlights/|title=Highlights: Python 2.5|website=Python.org|access-date=20 March 2018|archive-date=4 August 2019|archive-url=https://web.archive.org/web/20190804120408/https://www.python.org/download/releases/2.5/highlights/|url-status=live}}</ref> Examples of a context include acquiring a [[lock (computer science)|lock]] before some code is run, and then releasing the lock; or opening and then closing a [[Computer file|file]]
* The <code>[[break statement|break]]</code> statement, which exits a loop
* The <code>continue</code> statement, which skips the rest of the current iteration and continues with the next
* The <code>del</code> statement, which removes a variable—deleting the reference from the name to the value, and producing an error if the variable is referred to before it is redefined {{efn|<code>del</code> in Python does not behave the same way <code>delete</code> in languages such as [[C++]] does, where such a word is used to call the [[Destructor (computer programming)|destructor]] and deallocate heap memory.}} 
* The <code>pass</code> statement, serving as a [[NOP (code)|NOP]] (i.e., no operation), which is syntactically needed to create an empty code block
* The <code>[[assertion (programming)|assert]]</code> statement, used in debugging to check for conditions that should apply
* The <code>yield</code> statement, which returns a value from a [[generator (computer programming)#Python|generator]] function (and also an operator); used to implement [[coroutine]]s
* The <code>return</code> statement, used to return a value from a function
* The <code>[[include directive|import]]</code> and <code>from</code> statements, used to import modules whose functions or variables can be used in the current program
* The <code>match</code> and <code>case</code> statements, analogous to a [[switch statement]] construct, which compares an expression against one or more cases as a control-flow measure

The assignment statement (<code>=</code>) binds a name as a [[pointer (computer programming)|reference]] to a separate, dynamically allocated [[object (computer science)|object]]. Variables may subsequently be rebound at any time to any object. In Python, a variable name is a generic reference holder without a fixed [[Type system|data type]]; however, it always refers to ''some'' object with a type. This is called [[Type system#Dynamic type checking and runtime type information|dynamic typing]]—in contrast to [[statically-typed]] languages, where each variable may contain only a value of a certain type.

Python does not support [[tail call]] optimization or [[first-class continuations]]; according to Van Rossum, the language never will.<ref name="AutoNT-55"/><ref name="AutoNT-56"/> However, better support for [[coroutine]]-like functionality is provided by extending Python's generators.<ref name="AutoNT-57"/> Before 2.5, generators were [[lazy evaluation|lazy]] [[iterator]]s; data was passed unidirectionally out of the generator. From Python&nbsp;2.5 on, it is possible to pass data back into a generator function; and from version 3.3, data can be passed through multiple stack levels.<ref name="AutoNT-58"/>