code: def start(self, buffer):
          
          log.debug("In TftpContextServer.start")
          self.metrics.start_time = time.time()
          log.debug("Set metrics.start_time to %s", self.metrics.start_time)
          # And update our last updated time.
          self.last_update = time.time()
  
          pkt = self.factory.parse(buffer)
          log.debug("TftpContextServer.start() - factory returned a %s", pkt)
  
          # Call handle once with the initial packet. This should put us into
          # the download or the upload state.
          self.state = self.state.handle(pkt,
                                         self.host,
                                         self.port)
docs: Start the state cycle. Note that the server context receives an
          initial packet in its start method. Also note that the server does not
          loop on cycle(), as it expects the TftpServer object to manage
          that.