code: def test_excitations(electrons, orbitals, singles_ref, doubles_ref):
      r"""Test if the _excitations function returns correct single and double excitations."""
      singles, doubles = qchem.convert._excitations(electrons, orbitals)
      assert singles == singles_ref
      assert doubles == doubles_ref
  
imports: import os
  import sys
  import pytest
  import pennylane
  from pennylane import numpy
  from pennylane import qchem
  from pennylane.operation import disable_new_opmath, enable_new_opmath
label_desc: Use image node_id 20 for calling a global function with example usage: test_excitations(electrons, orbitals, singles_ref, doubles_ref) without return types