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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 total_scores_in(self, leaderboard_name):
        '''
        Sum of scores for all members in the named leaderboard.

        @param leaderboard_name Name of the leaderboard.
        @return Sum of scores for all members in the named leaderboard.
        '''
        return sum([leader[self.SCORE_KEY] for leader in self.all_leaders_from(self.leaderboard_name)])