import math


def get_radangle_flat_earth_old(pt1, pt2):
    """Get the angle for two given points (in flat earth coords)

    Arguments:
        pt1 {list} -- (x,y) for the first point
        pt2 {list} -- (x,y) for the first point

    Returns:
        float -- Angle (in radians) betweent pt1 and pt2
    """
    ydiff = pt1[1] - pt2[1]
    xdiff = pt1[0] - pt2[0]
    if abs(xdiff) < 1E-6:
        return math.pi / 2.0

    return math.atan(ydiff / float(xdiff))