new_contents: # -*- coding:utf-8 -*-
  
  from .data import ip_2_int
  
  def same_net(ip1, ip2, netmask):
      '''
          check if these two IP in the same subnet.
          input:
              ip1, ip2 : display string. e.g.: '192.168.2.33' or int
              netmask : display string. e.g.: '255.255.255.0' or int
      '''
      ip1 = ip_2_int(ip1)
      ip2 = ip_2_int(ip2)
      netmask = ip_2_int(netmask)
  
      return ip1 & netmask == ip2 & netmask
  
  
subject: add ip_util.py