code: def test_grid_2d_graph():
      # All minimum node cuts of a 2d grid
      # are the four pairs of nodes that are
      # neighbors of the four corner nodes.
      G = nx.grid_2d_graph(5, 5)
      solution = [
          {(0, 1), (1, 0)},
          {(3, 0), (4, 1)},
          {(3, 4), (4, 3)},
          {(0, 3), (1, 4)},
      ]
      for cut in nx.all_node_cuts(G):
          assert cut in solution
  
imports: import itertools
  import pytest
  import networkx
  from networkx.algorithms import flow
  from networkx.algorithms.connectivity.kcutsets import _is_separating_set
label_desc: Use image node_id 12 for calling a global function with example usage: test_grid_2d_graph() without return types