stretch.start()
stretch.start(audioContext.currentTime + 1)
stretch.stop()
stretch.stop(audioContext.currentTime + 3)
stretch.schedule({
	semitones: 5
})
stretch.schedule({
	semitones: 0,
	output: audioContext.currentTime + 3
})
stretch.schedule({
	rate: 0.8
})
stretch.schedule({
	input: 0, // start from beginning
	rate: 1.2,
	semitones: -2
})
stretch.schedule({
	input: 0,
	output: audioContext.currentTime + 1
}, true)