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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 wrap_errorhandler(app):
 """Wrap error handler. :param app: The Flask application. """

        try:
            existing_handler = app.error_handler_spec[None][404][NotFound]
        except (KeyError, TypeError):
            existing_handler = None

        if existing_handler:
            app.error_handler_spec[None][404][NotFound] = \
                lambda error: handle_not_found(error, wrapped=existing_handler)
        else:
            app.error_handler_spec.setdefault(None, {}).setdefault(404, {})
            app.error_handler_spec[None][404][NotFound] = handle_not_found