class_docstr: Unit tests for :func:`networkx.generators.lattice.grid_graph`
code: def test_periodic_iterable(self):
      m, n, k = 3, 7, 5
      for a, b, c in product([0, 1], [0, 1], [0, 1]):
          G = nx.grid_graph([m, n, k], periodic=(a, b, c))
          num_e = (
              (m + a - 1) * n * k
              + (n + b - 1) * m * k
              + (k + c - 1) * m * n
          )
          assert G.number_of_nodes() == m * n * k
          assert G.number_of_edges() == num_e
  
imports: from itertools import product
  import pytest
  import networkx
  from networkx.utils import edges_equal
label_desc: Use image node_id 3 for calling the TestGridGraph obj's underlying member method code with example usage: obj.test_periodic_iterable() without return types