code: function(error, method) {
      queued++;
      if (typeof wipe[method] == 'function') {
        wipe[method](function(err, removed) {
          if (err) last_err = err;
  
          removed += removed;
          --queued || finished(last_err);
        })
      } else return finished(error);
    }
docs: runs it within this context, unlike the spawn option