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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 register_error_handler( self, error: Union[Type[Exception], int], func: Callable, name: AppOrBlueprintKey=None, ) -> None: """Register a function as an error handler. This is designed to be used on the application directly. An example usage, .. code-block:: python def error_handler():
 return "Error", 500 app.register_error_handler(500, error_handler) Arguments: error: The error code or Exception to handle. func: The function to handle the error. name: Optional blueprint key name. """

        handler = ensure_coroutine(func)
        if isinstance(error, int):
            error = all_http_exceptions[error]
        self.error_handler_spec[name][error] = handler