In = function (v)
{
    v = 1 - v;

    if (v < 1 / 2.75)
    {
        return 1 - (7.5625 * v * v);
    }
    else if (v < 2 / 2.75)
    {
        return 1 - (7.5625 * (v -= 1.5 / 2.75) * v + 0.75);
    }
    else if (v < 2.5 / 2.75)
    {
        return 1 - (7.5625 * (v -= 2.25 / 2.75) * v + 0.9375);
    }
    else
    {
        return 1 - (7.5625 * (v -= 2.625 / 2.75) * v + 0.984375);
    }
}
Bounce ease-in.

@function Phaser.Math.Easing.Bounce.In
@since 3.0.0

@param {number} v - The value to be tweened.

@return {number} The tweened value.