def call_10(func):
    for i in range(10):
        func()
def print_hello():
    return 'hello'
call_10(print_hello)
but if
def call_10(func):
    for i in range(10):
        func()
def print_hello():
    print('hello')
call_10(print_hello)
it works! I want ask about difference
 
    