Method start

src/Animation.js:26–31

(
    fromValue: number,
    onUpdate: (value: number) => void,
    onEnd: ?EndCallback,
    previousAnimation: ?Animation,
  )

  __isInteraction: bool;
  __onEnd: ?EndCallback;
  start(
    fromValue: number,
    onUpdate: (value: number) => void,
    onEnd: ?EndCallback,
    previousAnimation: ?Animation,
  ): void {}
  stop(): void {}
  // Helper function for subclasses to make sure onEnd is only called once.
  __debouncedOnEnd(result: EndResult) {