docs: function runClean(options) {
      const platforms = detectPorting(options.platform);
      if (platforms.length <= 0) {
          return Promise.resolve();
      } else {
          platforms.forEach((platform) => {
              if ('dev' === platform) {
                  // app/porting
                  const dev_porting_dir = path.join(__dirname, '..', config.dir.src, config.dir.porting);
                  Object.keys(config.built_cleanee).forEach((key) => {
                      del.sync(config.built_cleanee[key], { cwd: dev_porting_dir });
                  });
              } else {
                  // platforms/<platform>/porting
                  const platform_porting_dir = path.join(__dirname, '../platforms', platform, config.dir.porting);
                  Object.keys(config.built_cleanee).forEach((key) => {
                      del.sync(config.built_cleanee[key], { cwd: platform_porting_dir });
                  });
                  // platforms/<platform>/platform_www/porting
                  const platform_www_porting_dir = path.join(__dirname, '../platforms', platform, 'platform_www', config.dir.porting);
                  del.sync(platform_www_porting_dir);
              }
          });
      }
  }