Your function fails on is_prime(3). It returns None when it should return True.

Upon testing, the code only fails when x == 3. Please help thanks!

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