def _add_left(self, d):
        '''
        Adds the provided domino to the left end of the board.

        :param Domino d: domino to add
        :return: None
        :raises EndsMismatchException: if the values do not match
        '''
        if not self:
            self.board.append(d)
        elif d.first == self.left_end():
            self.board.appendleft(d.inverted())
        elif d.second == self.left_end():
            self.board.appendleft(d)
        else:
            raise dominoes.EndsMismatchException(
                '{} cannot be added to the left of'
                ' the board - values do not match!'.format(d)
            )
Adds the provided domino to the left end of the board.

        :param Domino d: domino to add
        :return: None
        :raises EndsMismatchException: if the values do not match