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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 get_metric_index(self, data_source):
 """ This function will return the elasticsearch index for a corresponding data source. It chooses in between the default and the user inputed es indices and returns the user inputed one if it is available. :param data_source: the data source for which the index has to be returned :returns: an elasticsearch index name """


        if data_source in self.index_dict:
            index = self.index_dict[data_source]
        else:
            index = self.class2index[self.ds2class[data_source]]
        return Index(index_name=index)