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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def doc_subst(snippets):
 """ Substitute format strings in class or function docstring """

    def decorator(cls):
        # 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