@staticmethod
def offset_line(line, offset):
    """ Returns 'line' offset by 'offset'.

        'line' is a line segment of form [x0,y0,x1,y1].
        'offset' is an [x,y] point which is added to 'line'.

        Edge.offset_line(np.arr[float(x4)], arr[float(x2)]) -> arr[float(x4)]

        """
    return (line.reshape((2, 2)) + offset).reshape(4)
