public static Interpolator getFastOutSlowInInterpolator(Context context) {
        if (fastOutSlowIn == null) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                fastOutSlowIn = AnimationUtils.loadInterpolator(context,
                        android.R.interpolator.fast_out_slow_in);
            } else {
                fastOutSlowIn = new FastOutSlowInInterpolator();
            }
        }
        return fastOutSlowIn;
    }
Utility methods for working with animations.
library/src/main/java/com/heinrichreimersoftware/materialintro/util/AnimUtils.java