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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 value(self):
        '''The final value, if it has arrived

        :raises: AttributeError, if not yet complete
        :raises: an exception if the Future was :meth:`abort`\ed
        '''
        if not self._done.is_set():
            raise AttributeError("value")
        if self._failure:
            raise self._failure[0], self._failure[1], self._failure[2]
        return self._value