<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def map_or(self, callback: Callable[[T], U], default: A) -> Union[U, A]: """ Applies the ``callback`` to the contained value or returns ``default``. Args: callback: The callback to apply to the contained value. default: The default value. Returns: The ``callback`` result if the contained value is ``Some``, otherwise ``default``. Notes: If you wish to use the result of a function call as ``default``, it is recommended to use :py:meth:`map_or_else` instead. Examples: 1 1 """

        return callback(self._val) if self._is_some else default