Define a function called is_prime that takes a number x as input.

Oops, try again. Your function fails on is_prime(4). It returns True when it should return False.

```
def is_prime(x):
if(x==0 or x==1):
return False
n= x-1
while(n>1):
if x%n==0:
return False
break
else:
return True
n=n-1
else:
return True
```