code: def pytest_collection_modifyitems(config, items):
      requires_trainable_backend = pytest.mark.skipif(
          backend() == "numpy",
          reason="Trainer not implemented for NumPy backend.",
      )
      for item in items:
          if "requires_trainable_backend" in item.keywords:
              item.add_marker(requires_trainable_backend)
  
imports: import os
  import pytest
  from keras.backend import backend
label_desc: Use image node_id 2 for calling a global function with example usage: pytest_collection_modifyitems(config, items) without return types