I am stuck on function syntax no. 6 Practice Makes Perfect

It is returning an invalid syntax error message on statement (if number % 3 == 0)

this should allow the program to check if the number is divisible by three

```
def cube (number) :
return number ** 3
def by_three(number) :
if number % 3 == 0
return "n is divisible by 3"
else:
return "n is not"
cube(2)
by_three(2)
```