code: def do_async_send(self):
          
          assert len(self.sendbuf)
  
          nwritten = self.sock.send(self.sendbuf)
          nframes = 0
  
          for entry in self.sendbuf_frames:
              frame, offset, callback = entry
  
              if offset <= nwritten:
                  nframes += 1
  
                  if callback:
                      callback()
              else:
                  entry[1] -= nwritten
  
          self.sendbuf = self.sendbuf[nwritten:]
          self.sendbuf_frames = self.sendbuf_frames[nframes:]
docs: Send any queued data. This function should only be called after a write
          event on a file descriptor.