code: def test_add_single_var_adds_variable_node_as_expected(self):
      g = QueryGraph()
      g.add_vars(["a"])
      self.assertDictEqual({}, g.nodes["a"])
  
file_path: typedb-ml/typedb_ml/networkx/query_graph_test.py
imports: import unittest
  from typedb_ml.networkx.query_graph import QueryGraph
label_desc: Use image node_id 1 for calling the TestQueryGraph obj's underlying member method code with example usage: obj.test_add_single_var_adds_variable_node_as_expected() without return types