code: def test_write_interface(self):
      try:
          import lxml.etree
  
          assert nx.write_graphml == nx.write_graphml_lxml
      except ImportError:
          assert nx.write_graphml == nx.write_graphml_xml
  
imports: import io
  import pytest
  import networkx
  from networkx.readwrite.graphml import GraphMLWriter
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 2 for calling the TestWriteGraphML obj's underlying member method code with example usage: obj.test_write_interface() without return types