code: def test_labels_are_strings(self):
      # GML requires labels to be strings (i.e., in quotes)
      answer = """graph [
    node [
      id 0
      label "1203"
    ]
  ]"""
      G = nx.Graph()
      G.add_node(1203)
      data = "\n".join(
          nx.generate_gml(G, stringizer=literal_stringizer)
      )
      assert data == answer
  
imports: import codecs
  import io
  import math
  from ast import literal_eval
  from contextlib import contextmanager
  from textwrap import dedent
  import pytest
  import networkx
  from networkx.readwrite.gml import literal_destringizer, literal_stringizer
label_desc: Use image node_id 5 for calling the TestGraph obj's underlying member method code with example usage: obj.test_labels_are_strings() without return types