code: def on_start_tests(items):
      # Verify that items can be xfailed
      for item in items:
          assert hasattr(item, "add_marker")
  
file_path: networkx/networkx/classes/tests/dispatch_interface.py
imports: import networkx
  from networkx import DiGraph, Graph, MultiDiGraph, MultiGraph, PlanarEmbedding
  from networkx.classes.reportviews import NodeView
label_desc: Use image node_id 4 for calling the LoopbackDispatcher obj's underlying member method code with example usage: obj.on_start_tests(items) without return types