docs: function verifyInput(config) {
      if ('object' !== typeof config) {
          return 'config must be object.';
      }
      if ('string' !== typeof config.group) {
          return 'config.group must be string.';
      }
      if ('string' !== typeof config.name) {
          return 'config.name must be string.';
      }
      if (config.clients && !(config.clients instanceof PlayerList)) {
          return 'config.clients must be PlayerList or undefined.';
      }
      if (config.logicPath && 'string' !== typeof config.logicPath) {
          return 'config.logicPath must be string or undefined.';
      }
      if ('object' !== typeof config.channel) {
          return 'config.channel must be object.';
      }
      if (config.runtimeConf && 'object' !== typeof config.runtimeConf) {
          return 'config.channel must be object.';
      }
      return;
  }