def ut_get_email_from_ag_login_id(self, ag_login_id):
        """ Returns email for a given ag_login_id.
        For unit testing only!

        Parameters
        ----------
        ag_login_id : str
            Existing ag_login_id.

        Returns
        -------
        str: email
            Example: 'xX/tEv7O+T@6Ri7C.)LO'

        Raises
        ------
        ValueError
            If ag_login_id is not in DB.
        """
        with TRN:
            sql = """SELECT email
                     FROM ag.ag_login
                     WHERE ag_login_id=%s"""
            TRN.add(sql, [ag_login_id])
            info = TRN.execute_fetchindex()
            if not info:
                raise ValueError('No emails found.')
            return info[0][0]