def METHOD_NAME(cls, angle, ax, ay, az, degrees=False):
    """Classmethod to create a quaternion from an axis-angle representation. 
    (angle should be in radians).
    """
    if degrees:
        angle = np.radians(angle)
    while angle < 0:
        angle += np.pi*2
    angle2 = angle/2.0
    sinang2 = np.sin(angle2)
    return Quaternion(np.cos(angle2), ax*sinang2, ay*sinang2, az*sinang2)