outgoing.go
func (oa *OutgoingAudio) SetPerformer(to string) *OutgoingAudio {
	oa.Performer = to
	return oa
}
func (oa *OutgoingAudio) SetPerformer(to string) *OutgoingAudio {
	oa.Performer = to
	return oa
}
// SetPerformer sets a performer for the audio file (optional).