code: func (p *Client) WriteCharacteristic(c *ble.Characteristic, v []byte, noRsp bool) error {
  	p.Lock()
  	defer p.Unlock()
  	if noRsp {
  		return p.ac.WriteCommand(c.ValueHandle, v)
  	}
  	return p.ac.Write(c.ValueHandle, v)
  }
docs: // WriteCharacteristic writes a characteristic value to a server. [Vol 3, Part G, 4.9.3]