code: def is_ip_addr(self, ipstr):
          
          ipstr_chunks = ipstr.split('.')
          if len(ipstr_chunks) != 4:
              return False
          for ipstr_chunk in ipstr_chunks:
              if not ipstr_chunk.isdigit():
                  return False
              ipno_part = int(ipstr_chunk)
              if ipno_part < 0 or ipno_part > 255:
                  return False
          return True
docs: Convenience method to verify if string is an IP addr?
          :param ipstr: Stinrg containing IP address
          :rtype True if string is a valid IP address