by_three(1) returned None


HI Friends, please can SOMEONE help me with troubleshooting this python code:
it keeps giving me this error message:
Oops, try again. by_three(1) returned None, did you remember to return the result?

raw_input("Enter a number:")
def cube(number):
cubed = number ** 3
"""Print the cube of number"""
return cubed
print"the cube of %d is %(number, cubed)"

def by_three(number):
if number % 3 == 0:
return by_three(cubed)
print 'false'

Practice makes perfect help!

should read,

return cube(number)

and print 'false' should be,

return False

This line is not asked for.