anchor.diff:   * the result.
    */
   Future<bool> fileExists(file) {
  -  // TODO(nweiz): Currently File#exists will not detect the existence of
  -  // symlinks. Issue 2765
  -  return runProcess('stat', [_getPath(file)]).
  -    transform((result) => result.exitCode == 0);
  -
  -  // Real code:
  -  /*
     final completer = new Completer<bool>();
   
     file = new File(_getPath(file));
  
positive.code:   file.exists((exists) => completer.complete(exists));
  
    return completer.future;
    */
  }
  
  /**
  
negative.code:  * [Directory]. Returns a [Future] that completes when the deletion is done.
   */
  Future<Directory> deleteDir(dir) {
    final completer = new Completer<Directory>();
    dir = _getDirectory(dir);
    dir.onError = (error) => completer.completeException(error);
    dir.deleteRecursively(() => completer.complete(dir));
  
    return completer.future;
  }
  
  /**
  