code: def _do_packet_out(self, datapath, data, in_port, actions):
          
          ofproto = datapath.ofproto
          parser = datapath.ofproto_parser
  
          out = parser.OFPPacketOut(
              datapath=datapath, buffer_id=ofproto.OFP_NO_BUFFER,
              data=data, in_port=in_port, actions=actions)
          datapath.send_msg(out)
docs: send a packet.