code: def num_batch_dims(self):
      return self.batch_dims
  
file_path: stellargraph/tests/mapper/test_corrupted.py
imports: import pytest
  import numpy
  from stellargraph.mapper import *
  from ..test_utils.graphs import example_graph_random
label_desc: Use image node_id 3 for calling the DummyGenerator obj's underlying member method code with example usage: obj.num_batch_dims() and returns: self