code: def _iac_sniffer(self, byte):
          
          ## Are we not currently in an IAC sequence coming from the DE?
          if self.telnet_got_iac is False:
  
              if byte == IAC:
                  ## Well, we are now
                  self.telnet_got_iac = True
                  return
  
              ## Are we currenty in a sub-negotion?
              elif self.telnet_got_sb is True:
                  ## Sanity check on length
                  if len(self.telnet_sb_buffer) < 64:
                      self.telnet_sb_buffer += byte
                  else:
                      self.telnet_got_sb = False
                      self.telnet_sb_buffer = ""
                  return
  
              else:
                  ## Just a normal NVT character
                  self._recv_byte(byte)
                  return
  
          ## Byte handling when already in an IAC sequence sent from the DE
  
          else:
  
              ## Did we get sent a second IAC?
              if byte == IAC and self.telnet_got_sb is True:
                  ## Must be an escaped 255 (IAC + IAC)
                  self.telnet_sb_buffer += byte
                  self.telnet_got_iac = False
                  return
  
              ## Do we already have an IAC + CMD?
              elif self.telnet_got_cmd:
                  ## Yes, so handle the option
                  self._three_byte_cmd(byte)
                  return
  
              ## We have IAC but no CMD
              else:
  
                  ## Is this the middle byte of a three-byte command?
                  if byte == DO:
                      self.telnet_got_cmd = DO
                      return
  
                  elif byte == DONT:
                      self.telnet_got_cmd = DONT
                      return
  
                  elif byte == WILL:
                      self.telnet_got_cmd = WILL
                      return
  
                  elif byte == WONT:
                      self.telnet_got_cmd = WONT
                      return
  
                  else:
                      ## Nope, must be a two-byte command
                      self._two_byte_cmd(byte)
docs: Watches incomming data for Telnet IAC sequences.
          Passes the data, if any, with the IAC commands stripped to
          _recv_byte().