code: def test_const_covered_neighbors(self):
      G1 = nx.DiGraph([(0, 1), (1, 2), (0, 3), (2, 3)])
      G2 = nx.DiGraph([("a", "b"), ("b", "c"), ("a", "k"), ("c", "k")])
      gparams = _GraphParameters(G1, G2, None, None, None, None, None)
      sparams = _StateParameters(
          {0: "a", 1: "b", 2: "c"},
          {"a": 0, "b": 1, "c": 2},
          None,
          None,
          None,
          None,
          None,
          None,
          None,
          None,
      )
      u, v = 3, "k"
      assert _consistent_PT(u, v, gparams, sparams)
  
imports: import itertools
  import pytest
  import networkx
  from networkx import vf2pp_is_isomorphic, vf2pp_isomorphism
  from networkx.algorithms.isomorphism.vf2pp import _consistent_PT, _cut_PT, _feasibility, _find_candidates, _find_candidates_Di, _GraphParameters, _initialize_parameters, _matching_order, _restore_Tinout, _restore_Tinout_Di, _StateParameters, _update_Tinout
label_desc: Use image node_id 1 for calling the TestDiGraphISOFeasibility obj's underlying member method code with example usage: obj.test_const_covered_neighbors() without return types