OptionalEffectTiming constructor
      
      OptionalEffectTiming({})
     
    
    
Implementation
factory OptionalEffectTiming(
        {double? delay,
        double? endDelay,
        FillMode? fill,
        double? iterationStart,
        /* double | NaN */ dynamic iterations,
        dynamic duration,
        PlaybackDirection? direction,
        String? easing}) =>
    OptionalEffectTiming._(
        delay: delay ?? undefined,
        endDelay: endDelay ?? undefined,
        fill: fill?.value ?? undefined,
        iterationStart: iterationStart ?? undefined,
        iterations: iterations ?? undefined,
        duration: duration ?? undefined,
        direction: direction?.value ?? undefined,
        easing: easing ?? undefined);