message: return the progress computed by the internal part
diff: @@ -281,6 +281,10 @@ export class Sequence<ValueType = any> extends ToneEvent<ValueType> {
  this._part.probability = prob;
  }
  + get progress(): NormalRange {
  + return this._part.progress;
  + }
  +
  get humanize(): boolean | Time {
  return this._part.humanize;
  }
  