code: def test_er_graph():
      graph_generator = ERGraph(num_nodes=300, edge_prob=0.1)
      assert (
          str(graph_generator)
          == "ERGraph(num_nodes=300, edge_prob=0.1)"
      )
  
      data = graph_generator()
      assert len(data) == 2
      assert data.num_nodes == 300
      assert data.num_edges >= 300 * 300 * 0.05
      assert data.num_edges <= 300 * 300 * 0.15
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_er_graph() without return types