How to annotate a generator in python3?

Question

Python 3.x supports (optional) function annotations:

def add_ints(x:int, y:int) -> int :
    return x+y

I sometimes encounter problems as to

Answer 1

The typing module defines the Generator type, which you can use like:

Generator[yield_type, send_type, return_type] 

See also PEP 0484.