code: function _readFileOnEnd(filename, contents, cache) {
    loading--;
    const data = Buffer.concat(contents);
    cache.set(filename, data);
    _fireReadFileCallbacks(filename, data);
    _runFileQueue();
  }
docs: On end listener for readFile.
  
  @private
  @param {string} filename           The filename.
  @param {Array.<Buffer>} contents   The file contents as a series of buffers.
  @param {Map} cache                 The file cache.