envelopeStageFromInt function
Implementation
EnvelopeStage envelopeStageFromInt(int i) {
switch(i){
case 0: return EnvelopeStage.delay;
case 1: return EnvelopeStage.attack;
case 2: return EnvelopeStage.hold;
case 3: return EnvelopeStage.decay;
case 4: return EnvelopeStage.release;
}
throw "invalid VoiceEnvStage $i";
}