python - Prime numbers multiplied by 3 shown as prime numbers -

i trying create function in python checks whether given number prime number, wrote code:

def is_prime(x):     if x<2:         return false     elif x==2:         return true     else:         n in range(2,x):             if (x%n)==0:                 return false             else:                 return true 

for reason, every number sum of (prime_number*3) shown prime number (for example, these shown prime numbers: 9,21,15,25...) can see problem code?

this happens, because return is_prime on first iteration of loop. test if x dividable 2, return true if , false otherwise.

remove else clause loop , return true after has ended.

def is_prime(x):     if x<2:         return false     elif x==2:         return true     else:         n in range(2,x):             if (x%n)==0:                 return false         return true