This module provides a type that represents a Python with item.
Example: The statement with (f() as a, g()): ... contains 2 with items. The first one has f() as its context_expr and a as its optional_vars. The second one has g() as its context_expr and no optional_vars.
Note that optional_vars is "target"-like: It can only be one of a selected few kinds of expressions, and the corresponding expression context will always be set to ExpressionContext.t.store. See documentation of ExpressionContext for more details of which expressions are allowed.