code: def test_imports():
      for layer in federation_hierarchy:
          packages = federation_hierarchy[layer]
          for package in packages:
              assert module_exists(package), f"{package} not installed."
  
imports: from pkgutil import iter_modules
  from pysal import federation_hierarchy
label_desc: Use image node_id 2 for calling a global function with example usage: test_imports() without return types