anchor.diff:  
   library git.commands.diff;
   
  -import 'dart:async';
  -import 'dart:typed_data';
  -
  -import '../diff3.dart';
   import '../object.dart';
  -import '../object_utils.dart';
  -import '../objectstore.dart';
  -import '../utils.dart';
  -
  -class MergeItem {
  -  TreeEntry ours;
  -  TreeEntry base;
  -  TreeEntry theirs;
  -  String conflictText;
  -  bool isConflict;
  -
  -  MergeItem(this.ours, this.base, this.theirs, [this.isConflict = false]);
  -}
   
   class DiffEntryType {
     static const String ADDED = "ADDED";
  
positive.code:   // String representation of the diff between the two versions of file.
    String diff;
    String type;
    DiffEntry(this.oldEntry, this.newEntry, this.type,  [this.path, this.diff]);
  }
  
  class TreeDiffResult {
  
negative.code: 
  /**
   * Implements tree diffs.
   *
   * TODO(grv): add unittests.
   */
  class Diff {
  
    static TreeDiffResult diffTree(TreeObject oldTree, TreeObject newTree) {
      oldTree.sortEntries();
  