'Add member to the member list.
:param member_dn: DN of member to be added.
:param member_list_dn: DN of group to which the
member will be added.
:raises keystone.exception.Conflict: If the user was already a member.
:raises self.NotFound: If the group entry didn\'t exist.'

def add_member(self, member_dn, member_list_dn):

    with self.get_connection() as conn:
        try:
            mod = (ldap.MOD_ADD, self.member_attribute, member_dn)
            conn.modify_s(member_list_dn, [mod])
        except ldap.TYPE_OR_VALUE_EXISTS:
            raise exception.Conflict((_('Member    %(member)s    is    already    a    member    of    group    %(group)s') % {'member': member_dn, 'group': member_list_dn}))
        except ldap.NO_SUCH_OBJECT:
            raise self._not_found(member_list_dn)
