Merges the original dataframe with corresponding entity uuids based
        on the given columns. Also merges other additional information
        associated to uuids provided in the uuids dataframe, if any.

        :param columns: columns to match for merging
        :type column: string array

        :return: original dataframe with at least one new column:
         * uuid: identity unique identifier
        :rtype: pandas.DataFrame

def enrich(self, columns):
        """ Merges the original dataframe with corresponding entity uuids based
        on the given columns. Also merges other additional information
        associated to uuids provided in the uuids dataframe, if any.

        :param columns: columns to match for merging
        :type column: string array

        :return: original dataframe with at least one new column:
         * uuid: identity unique identifier
        :rtype: pandas.DataFrame
        """

        for column in columns:
            if column not in self.data.columns:
                return self.data

        self.data = pandas.merge(self.data, self.uuids_df, how='left', on=columns)
        self.data = self.data.fillna("notavailable")

        return self.data