docs: def is_group_valid(self, groupID):
          """
          Check if this group ID is valid.
          """
          cur = self.conn.cursor()
          cur.execute('SELECT * FROM groups WHERE id=? LIMIT 1', [groupID])
          results = cur.fetchall()
          cur.close()
  
          logging.debug('is_group_valid(groupID={}) => {}'.format(groupID, True if len(results) else False))
          return len(results) > 0