code: func (nc *Conn) clearPendingFlushCalls() {
  	// Clear any queued pongs, e.g. pending flush calls.
  	for _, ch := range nc.pongs {
  		if ch != nil {
  			close(ch)
  		}
  	}
  	nc.pongs = nil
  }
docs: // This will clear any pending flush calls and release pending calls.
  // Lock is assumed to be held by the caller.