code: func (r *selectResult) Close() error {
  	// Close this channel tell fetch goroutine to exit.
  	if r.feedback.Actual() >= 0 {
  		metrics.DistSQLScanKeysHistogram.Observe(float64(r.feedback.Actual()))
  	}
  	metrics.DistSQLPartialCountHistogram.Observe(float64(r.partialCount))
  	close(r.closed)
  	return r.resp.Close()
  }
docs: // Close closes selectResult.