def _k_simplex_neighbor_index_list(d, k):
    """Given a d-simplex with d being 2 or 3, indexes for neighbor simplexes in the scipy.Delaunay triangulation
    are provided for all k-simplices with k<d that are part of the d-simplex."""
    if d == 2 and k == 1:
        return 2, 0, 1
    elif d == 3 and k == 2:
        return 3, 2, 1, 0
    else:
        raise ValueError