code: def test_generator_hin():
      graphs_mixed = [
          example_graph_random(feature_size=2, n_nodes=6),
          example_hin_1(is_directed=False),
      ]
  
      with pytest.raises(
          ValueError,
          match="graphs: expected only graphs with a single node type.*found.*'A', 'B'",
      ):
          generator = PaddedGraphGenerator(graphs=graphs_mixed)
  
      generator = PaddedGraphGenerator(graphs=graphs_mixed[:1])
      with pytest.raises(
          ValueError,
          match="graphs: expected only graphs with a single node type.*found.*'A', 'B'",
      ):
          seq = generator.flow(graphs_mixed)
  
imports: from stellargraph.core.graph import *
  from stellargraph.mapper.padded_graph_generator import PaddedGraphGenerator, PaddedGraphSequence
  import numpy
  import pytest
  from ..test_utils.graphs import example_graph_random, example_graph, example_hin_1
label_desc: Use image node_id 5 for calling a global function with example usage: test_generator_hin() without return types