Why does my function stop working on the number 9? In looking at my function, when I go through and test the number 9 in the equations, it seems like it should work out and return False. But I receive this error message: "Oops, try again. Your function fails on is_prime(9). It returns True when it should return False."

The code works with other numbers (both prime and not prime) from 4 to 8. What's happening here?

```
if x <= 1:
return False
elif x == 2 or x == 3:
return True
else:
for n in range (2, x-1):
if x % n == 0:
return False
else:
return True
```

Any help or advice is greatly appreciated.