code: def test_get_contact_atom_indices(self):
      complexes = rdkit_utils.load_complex(
          [self.protein_file, self.ligand_file]
      )
      contact_indices = get_contact_atom_indices(complexes)
      assert len(contact_indices) == 2
  
file_path: deepchem/deepchem/utils/test/test_fragment_utils.py
imports: import os
  import unittest
  import numpy
  from deepchem.utils import rdkit_utils
  from deepchem.utils.fragment_utils import get_contact_atom_indices
  from deepchem.utils.fragment_utils import merge_molecular_fragments
  from deepchem.utils.fragment_utils import get_partial_charge
  from deepchem.utils.fragment_utils import strip_hydrogens
  from deepchem.utils.fragment_utils import MolecularFragment
  from deepchem.utils.fragment_utils import AtomShim
label_desc: Use image node_id 2 for calling the TestFragmentUtil obj's underlying member method code with example usage: obj.test_get_contact_atom_indices() without return types