def classify_turn_direction(relative_azimuth, straight_angle=20):
    """Classify turn directions based on a relative azimuth     
    """
    if (relative_azimuth < straight_angle) or (relative_azimuth > (360 - straight_angle)):
        return 'straight'
    elif (relative_azimuth >= straight_angle) and (relative_azimuth <= (180 - straight_angle)):
        return 'left'
    elif (relative_azimuth > (180 - straight_angle)) and (relative_azimuth < (180 + straight_angle)):
        return 'U'
    elif (relative_azimuth >= (180 + straight_angle)) and (relative_azimuth <= (360 - straight_angle)):
        return 'right'