code: def test_functional():
      settings = Settings()
      settings._declare("foo", str, default="bar")
  
      assert settings.foo == "bar"
  
file_path: gluonts/test/core/test_settings.py
imports: from gluonts.core.settings import Settings, let
  from gluonts.pydantic import BaseModel
label_desc: Use image node_id 1 for calling a global function with example usage: test_functional() without return types