code: def test_add_walk(self):
      kg = KG(skip_predicates={f"{URL}#predicate"})
      for row in GRAPH:
          subj = Vertex(f"{URL}#{row[0]}")
          obj = Vertex((f"{URL}#{row[2]}"))
          pred = Vertex(
              (f"{URL}#{row[1]}"), predicate=True, vprev=subj, vnext=obj
          )
          assert kg.add_walk(subj, pred, obj) is True
      subj = Vertex(f"{URL}#{GRAPH[0][0]}")
      obj = Vertex(f"{URL}#{GRAPH[0][2]}")
      pred = Vertex(f"{URL}#predicate")
      assert kg.add_walk(subj, pred, obj) is False
  
imports: import numpy
  import pytest
  from pyrdf2vec.graphs import KG, Vertex
label_desc: Use image node_id 2 for calling the TestKG obj's underlying member method code with example usage: obj.test_add_walk() without return types