code: func (c *Characteristic) HandleRead(h ReadHandler) {
  	if c.Value != nil {
  		panic("charactristic has been configured with a static value")
  	}
  	c.Property |= CharRead
  	c.ReadHandler = h
  }
docs: // HandleRead makes the characteristic support read requests, and routes read requests to h.
  // HandleRead must be called before the containing service is added to a server.
  // HandleRead panics if the characteristic has been configured with a static value.