old_contents: /* This file is part of Indico.
   * Copyright (C) 2002 - 2018 European Organization for Nuclear Research (CERN).
   *
   * Indico is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 3 of the
   * License, or (at your option) any later version.
   *
   * Indico is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with Indico; if not, see <http://www.gnu.org/licenses/>.
   */
  
  export function toClasses(obj) {
      return Object.entries(obj).map(
          ([k, v]) => (v ? ` ${k}` : '')
      ).join('').trim();
  }
  
new_contents: /* This file is part of Indico.
   * Copyright (C) 2002 - 2018 European Organization for Nuclear Research (CERN).
   *
   * Indico is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 3 of the
   * License, or (at your option) any later version.
   *
   * Indico is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with Indico; if not, see <http://www.gnu.org/licenses/>.
   */
  
  export function toClasses(...params) {
      const obj = params.length === 1 ? params[0] : params;
      if (Array.isArray(obj)) {
          return obj.join(' ').trim();
      } else if (typeof obj === 'string') {
          return obj;
      }
      return Object.entries(obj).map(
          ([k, v]) => (v ? ` ${k}` : '')
      ).join('').trim();
  }
  
subject: Make toClasses(...) more flexible regarding input