well,I have got the right answer.
But I really want to know:why I can`t use "return" this way
It's simple actually.
return wont print your result, and you need it printed. You want to use it this way?
Call function like this:
print power(37, 4)
But you must print the result. Either as part of function, or return it from function and print it outside.
thank you for your reply,I got it !