code: def unbuffered_write(self, buf):
          
          if self.closed:
              raise ConnectionClosed()
  
          result = 0
          try:
              result = self.sock.send(buf)
          except EnvironmentError as e:
              # if the socket is simply backed up ignore the error 
              if e.errno != errno.EAGAIN: 
                  self._close(e)
                  return
  
          # when the socket buffers are full/backed up then we need to poll to see
          # when we can write again
          if result != len(buf):
              self.write = self.buffered_write
              self.write_watcher.start()
              self.write(buf[result:])
docs: Performs an unbuffered write, the default unless socket.send does
          not send everything, in which case an unbuffered write is done and the
          write method is set to be a buffered write until the buffer is empty
          once again.
  
          buf -- bytes to send