static isFastSwitching(variant) {
    if (variant.audio && variant.audio.fastSwitching) {
      return true;
    }
    if (variant.video && variant.video.fastSwitching) {
      return true;
    }
    return false;
  }
Indicates if some of the variant's streams are fastSwitching.

@param {shaka.extern.Variant} variant
@return {boolean}