def bisect(V1, V2):
    """Bisects two vectors V1 and V2. Returns a vector."""

    # from https://math.stackexchange.com/questions/2285965/how-to-find-the-vector-formula-for-the-bisector-of-given-two-vectors

    V = V1.norm() * V2 + V2.norm() * V1
    return V / V.norm()