code: def doc_subst(snippets):
      """Substitute format strings in class or function docstring"""
  
      def decorator(cls):
          # Running python with -OO will discard docstrings (__doc__ is None).
          if cls.__doc__ is not None:
              # Strip the snippets to avoid trailing new lines and whitespace
              stripped_snippets = {
                  key: snippet.strip()
                  for (key, snippet) in snippets.items()
              }
              cls.__doc__ = cls.__doc__.format(**stripped_snippets)
          return cls
  
      return decorator
  
label_desc: Use image node_id 1 for calling a global function with example usage: doc_subst(snippets) and returns: decorator, cls