code: @NonNull
      public IconicsAnimationProcessor interpolator(@NonNull TimeInterpolator interpolator) {
          if (interpolator != null) {
              mInterpolator = interpolator;
          } else {
              mInterpolator = sDefaultInterpolator;
          }
          return this;
      }
docs: The time interpolator used in calculating the elapsed fraction of this animation. The
  interpolator determines whether the animation runs with linear or non-linear motion,
  such as acceleration and deceleration. The default value is
  {@link android.view.animation.LinearInterpolator}
  
  @param interpolator the interpolator to be used by this processor. A value of {@code null}
  will result in linear interpolation.