def angle_between(last_angle, this_angle):
    """
    >>> angle_between(50.0, 50.0)
    0.0
    >>> angle_between(60.0, 50.0)
    -10.0
    >>> angle_between(50.0, 60.0)
    10.0
    >>> angle_between(350.0, 5.0)
    15.0
    >>> angle_between(5.0, 350.0)
    -15.0
    """

    turn_angle = (this_angle - last_angle) % 360
    turn_angle = turn_angle - 360 if turn_angle > 180 else turn_angle

    return turn_angle