yield_stmt ::= yield_expression
A yield statement is semantically equivalent to a yield expression. The yield statement can be used to omit the parentheses that would otherwise be required in the equivalent yield expression statement. For example, the yield statements
yield <expr>
yield from <expr>
are equivalent to the yield expression statements
(yield <expr>)
(yield from <expr>)
Yield expressions and statements are only used when defining a generator function, and are only used in the body of the generator function. Using yield in a function definition is sufficient to cause that definition to create a generator function instead of a normal function.
For full details of yield semantics, refer to the Yield expressions section.