code: function() {
      var r = [];
      for (var i = 0; i < fls.length; i += 2) {
        if (fls[i + 1]) {
          r.push(fls[i]);
        } else {
          r = fls[i + 1] === false ? fls[i] : null;
          break;
        }
      }
      return r;
    }
docs: Check results
  @return {mixed} array -- files list
  string -- error
  null -- loading yet