code: function addFileToQueue(filename, callback){
    if (processingPaths[filename]) {
      if (typeof callback == 'function')
        processingPaths[filename].unshift(callback);
  
      return;
    }
  
    processingPaths[filename] = typeof callback == 'function'
      ? [callback].concat(readCallbacks)
      : readCallbacks.slice();
  
    if (readingCount < READ_LIMIT)
      readFile(filename);
    else
    {
      logMsg('fs', relativePath(filename) + ' ' + chalk.yellow('(add file to queue)'), true);
      filesToRead.push(filename);
    }
  }
docs: processingPaths[key] -> [callbackN .. callback1 onRead1 ... onReadN]