Slope = function (line)
{
    return (line.y2 - line.y1) / (line.x2 - line.x1);
}
Calculate the slope of the given line.

@function Phaser.Geom.Line.Slope
@since 3.0.0

@param {Phaser.Geom.Line} line - The line to calculate the slope of.

@return {number} The slope of the line.