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

In this line, I keep getting 4 to come up True when it should be False. Help!!