title: 'None' is printed when I want 'True' for input 5
body: <p>In this primality test program, 'None' is printed when I input a prime, instead of 'True'. How can I get it to print 'True'?. </p>
  
  <pre><code>    def main():
          import math
          def check_n(n):
              n_s = int(math.sqrt(n))
              for i in range(2, n_s):
                  if (n_s % i) == 0:
                      return False
                      break
                  else:
                      return True
          def msg():
              n = int(input('Enter a number, I will return True if it is a prime'))
              return n
  
          print(check_n(msg()))
  
      main()
  </code></pre>