initialize method
Base method for instance initialization
After you call this method set isInitialized flag to true
input - input for this instance
Implementation
@mustCallSuper
void initialize(T input) {
  this.input = input;
  initializeSub();
  isPaused = false;
  allPartsReady.update(false);
  initializeInstanceParts();
  if (!isAsync) {
    isInitialized = true;
  }
}