syntax except* in Python 3.11 for exception groups); it also ensures that clean-up code in a finally block is always run regardless of how the block exits The raise statement, used to raise a specified exception or re-raise a caught exception The class statement, which executes a block of code and attaches its local namespace to a class, for use in object-oriented programming The def statement, which defines a function or method The with statement, which encloses a code block within a context manager (for example, acquiring a lock before it is run, then releasing the lock; or opening and closing a file), allowing resource-acquisition-is-initialization (RAII)-like behavior and replacing a common try/finally idiom The break statement, which exits a loop The continue statement, which skips the rest of the current iteration and continues with the next The del 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 The pass statement, serving as a NOP, syntactically needed to create an empty code block The assert statement, used in debugging to check for conditions that should apply The yield statement, which returns a value from a generator function (and also an operator); used to implement coroutines The return statement, used to return a value from a function The import and from statements, used to import modules whose functions or variables can be used in the current program The assignment statement (=) binds a name as a reference to a separate, dynamically allocated 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 data type; however, it always refers to some object with a type. This is called 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, and, according to Van Rossum, it never will. However, better support for coroutine-like functionality is provided by extending Python's generators. Before 2.5, generators were lazy iterators; data was passed unidirectionally out of the generator. From Python 2.5 on, it is possible to pass data back into a generator function; and from version 3.3, it can be passed through multiple stack levels. Expressions Python's expressions include: The +, -, and * operators for mathematical addition,