def main():

n = input("Please enter a number:")
is_prime(n)
def is_prime(a):
x = True
for i in (2, a):
while x:
if a%i == 0:
x = False
else:
x = True
if x:
print "prime"
else:
print "not prime"
main()

If the entered number is not a prime number, it displays "not prime", as it is supposed to, but if the number is a prime number, it doesn't display anything. Could you please help me with it?