def cross3(v1, v2):
    """
    Quick convenient function to compute cross product betwee two 3-element vectors
    cross3: 326 ns | np.cross: 35.8 us
    """
    a1, a2, a3 = v1
    b1, b2, b3 = v2
    return [a2 * b3 - a3 * b2, a3 * b1 - a1 * b3, a1 * b2 - a2 * b1]
