code: def test_get_max_ents_index(data_indexer):
      max_ents = data_indexer.backend._get_max_ents_index()
      assert (
          max_ents == 3
      ), "Max index should be 3 for 4 unique entities, instead got {}.".format(
          max_ents
      )
  
file_path: AmpliGraph/tests/ampligraph/datasets/test_data_indexer.py
imports: from ampligraph.datasets.data_indexer import DataIndexer
  import numpy
  import pytest
label_desc: Use image node_id 4 for calling a global function with example usage: test_get_max_ents_index(data_indexer) without return types