code: def test_unused_keys(self):
      snippets = {"key": "62", "other-key": "unused"}
  
      @doc_subst(snippets)
      def f():
          """Docstring with value {key}"""
  
      assert f.__doc__ == " Docstring with value 62 "
  
imports: from unittest import TestCase
  from ipywidgets.widgets.docutils import doc_subst
label_desc: Use image node_id 2 for calling the TestDocSubst obj's underlying member method code with example usage: obj.test_unused_keys() without return types