def print_square(number):
    print(number * number)

def return_square(number):
    return number * number

# what will be displayed if the following is typed
# into the python shell?
#
# print_square(10)
# return_square(10)
#
# x = print_square(10)
# x
# y = return_square(10)
# y

# what will happen if the following was included at the bottom
# of the code when we run this program?
#print_square(5)
#return_square(5)
#print(print_square(5))
#print(return_square(5))