docs: function assignIfFunction(name, toObj, fromObj, where) {
      if ('undefined' !== typeof fromObj[name]) {
          if ('function' !== typeof fromObj[name]) {
              new TypeError((where || 'WaitingRoom.parseSettings: ') + name +
                            'must be function or undefined. Found: ' +
                            fromObj[name]);
          }
          toObj[name] = fromObj[name];
      }
  }