Angle = function (line)
{
    return Math.atan2(line.y2 - line.y1, line.x2 - line.x1);
}
Calculate the angle of the line in radians.

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

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

@return {number} The angle of the line, in radians.