func (c *Context) IsReady() bool {
	c.m.Lock()
	r := c.ready
	c.m.Unlock()
	return r
}
func (c *Context) IsReady() bool {
	c.m.Lock()
	r := c.ready
	c.m.Unlock()
	return r
}
// IsReady returns a boolean value indicating whether the audio is ready or not.
//
// On some browsers, user interaction like click or pressing keys is required to start audio.