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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 shell_context_processor(self, func: Callable) -> Callable: """Add a shell context processor. This is designed to be used as a decorator. An example usage, .. code-block:: python @app.shell_context_processor def additional_context():
 return context """

        self.shell_context_processors.append(func)
        return func