. Loops: Practise Makes Perfect: 6. is_prime

All answers seem to return 'None'

```
def is_prime(x):
if x < 2:
return False
else:
for n in range(2, x):
if x % n == 0:
return False
else:
return True
```

Is putting a function parameter as an argument of range (I hope I got that right...) not allowed?