FadeOut constructor
      
      FadeOut(})
     
    
    
Implementation
FadeOut(
  Mobject mobject, {
  double runTime = DEFAULT_ANIMATION_RUN_TIME,
  RateFunc rateFunc = smooth,
  double lagRatio = DEFAULT_ANIMATION_LAG_RATIO,
}) : super(mobject, runTime: runTime, rateFunc: rateFunc, lagRatio: lagRatio);