code: function validateFileset(fileset, setter) {
      if (Array.isArray(fileset)) {
          async.each(fileset, function(path, callback) {
              if (typeof path === 'string') {
                  callback();
              } else {
                  callback(util.format('Invalid path: %s', path));
              }
          }, function(err) {
              if (err) {
                  console.log(chalk.red(err));
              } else {
                  setter(fileset);
              }
          });
      } else {
          console.log(chalk.red('Fileset is not an array: %j'), fileset);
      }
  }
docs: Filesets are validated by ensuring the fileset is an array and each item is a string. Valid filesets are applied, invalid ones are ignored.