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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 name_columns(self, sub):
 """ Substitutes the split column index with a human readable string """

        if self.column_id is not None and len(sub) > self.column_id:
            self.split_name = sub[self.column_id]
        for split in self.surrogates:
            split.name_columns(sub)