Out = function (v, overshoot)
{
    if (overshoot === undefined) { overshoot = 1.70158; }

    return --v * v * ((overshoot + 1) * v + overshoot) + 1;
}
Back ease-out.

@function Phaser.Math.Easing.Back.Out
@since 3.0.0

@param {number} v - The value to be tweened.
@param {number} [overshoot=1.70158] - The overshoot amount.

@return {number} The tweened value.