anchor.diff:  
   /// Returns the name of the git command-line app, or `null` if Git could not be
   /// found on the user's PATH.
  -String get command {
  +String? get command {
     if (_commandCache != null) return _commandCache;
   
     if (_tryGitCommand('git')) {
  
positive.code: /// Returns the stdout as a list of strings if it succeeded. Completes to an
  /// exception if it failed.
  Future<List<String>> run(List<String> args,
      {String workingDir, Map<String, String> environment}) async {
    if (!isInstalled) {
      fail('Cannot find a Git executable.\n'
          'Please ensure Git is correctly installed.');
  
negative.code: // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  // for details. All rights reserved. Use of this source code is governed by a
  // BSD-style license that can be found in the LICENSE file.
  
  /// Helper functionality for invoking Git.
  import 'dart:async';
  