import importlib.util
import numpy as np
s = importlib.util.spec_from_file_location("sp", "sandpile.py"); m = importlib.util.module_from_spec(s); s.loader.exec_module(m)
want = {2: [[2, 2], [2, 2]], 3: [[2, 1, 2], [1, 0, 1], [2, 1, 2]]}
for n, w in want.items():
    e = m.identity(n, 6)
    print("N=%d identity %s | DRSV95 eq. (7.11) %s | equal: %s" % (n, e.tolist(), w, bool(np.array_equal(e, np.array(w)))))