radio.go
func (c *Radio) OnChange(fn func(bool)) {
	c.mtx.Lock()
	defer c.mtx.Unlock()

	c.onChange = fn
}
func (c *Radio) OnChange(fn func(bool)) {
	c.mtx.Lock()
	defer c.mtx.Unlock()

	c.onChange = fn
}
// OnChange sets the callback that is called whenever the state
// of the Radio is changed. Argument of callback is the current