demonstrate_yield.py

def fun_return(n):
    print("Run fun_return")
    lst = list()
    for i in range(n):
        print("Run loop in fun_return")
        lst.append(i * i)
    return lst


def fun_yield(n):
    print("Run fun_yield")
    for i in range(n):
        print("Run loop in fun_yield")
        yield i * i


alist = fun_return(4)
for i2 in alist:
    print("Run main loop from fun_return", i2)

generator = fun_yield(4)
for i2 in generator:
    print("Run main loop from fun_yield", i2)

The result is:

Run fun_return
Run loop in fun_return
Run loop in fun_return
Run loop in fun_return
Run loop in fun_return
Run main loop from fun_return 0
Run main loop from fun_return 1
Run main loop from fun_return 4
Run main loop from fun_return 9
Run fun_yield
Run loop in fun_yield
Run main loop from fun_yield 0
Run loop in fun_yield
Run main loop from fun_yield 1
Run loop in fun_yield
Run main loop from fun_yield 4
Run loop in fun_yield
Run main loop from fun_yield 9