code: func Mute(b bool) Option {
  	return Option(func(c *config) {
  		c.Client.Muted = b
  	})
  }
docs: // Mute sets whether the Client is muted. All methods of a muted Client do
  // nothing and return immedialtly.
  //
  // This option can be used in Client.Clone() only if the parent Client is not
  // muted. The clones of a muted Client are always muted.