code: def test_dls_successor(self):
      result = nx.dfs_successors(self.G, source=4, depth_limit=3)
      assert {n: set(v) for n, v in result.items()} == {
          2: {1, 7},
          3: {2},
          4: {3, 5},
          5: {6},
      }
      result = nx.dfs_successors(self.D, source=7, depth_limit=2)
      assert {n: set(v) for n, v in result.items()} == {
          8: {9},
          2: {3},
          7: {8, 2},
      }
  
imports: import networkx
label_desc: Use image node_id 4 for calling the TestDepthLimitedSearch obj's underlying member method code with example usage: obj.test_dls_successor() without return types