code: def test_grid_3d_7():
      """Check that the grid graph is symmetric"""
      xyz = np.array(np.where(np.random.rand(5, 5, 5) > 0.5)).T
      adj = wgraph_from_3d_grid(xyz, 6).to_coo_matrix()
      assert (adj - adj.T).nnz == 0
      adj = wgraph_from_3d_grid(xyz, 18).to_coo_matrix()
      assert (adj - adj.T).nnz == 0
      adj = wgraph_from_3d_grid(xyz, 26).to_coo_matrix()
      assert (adj - adj.T).nnz == 0
  
imports: import numpy
  import numpy.random
  from numpy.testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal
  from ..graph import WeightedGraph, complete_graph, concatenate_graphs, eps_nn, knn, mst, wgraph_from_3d_grid, wgraph_from_adjacency, wgraph_from_coo_matrix
label_desc: Use image node_id 18 for calling a global function with example usage: test_grid_3d_7() without return types