def enrich(self, column1, column2):
        """ This class splits those commits where column1 and column2
        values are different

        :param column1: column to compare to column2
        :param column2: column to compare to column1
        :type column1: string
        :type column2: string

        :returns: self.commits with duplicated rows where the values at
            columns are different. The original row remains while the second
            row contains in column1 and 2 the value of column2.
        :rtype: pandas.DataFrame
        """

        if column1 not in self.commits.columns or \
           column2 not in self.commits.columns:
            return self.commits

        # Select rows where values in column1 are different from
        # values in column2
        pair_df = self.commits[self.commits[column1] != self.commits[column2]]
        new_values = list(pair_df[column2])
        # Update values from column2
        pair_df[column1] = new_values

        # This adds at the end of the original dataframe those rows duplicating
        # information and updating the values in column1
        return self.commits.append(pair_df)
This class splits those commits where column1 and column2
        values are different

        :param column1: column to compare to column2
        :param column2: column to compare to column1
        :type column1: string
        :type column2: string

        :returns: self.commits with duplicated rows where the values at
            columns are different. The original row remains while the second
            row contains in column1 and 2 the value of column2.
        :rtype: pandas.DataFrame