anchor.diff:     */
     Map<String, String> toMap() {
       return {
  -            "commit": _sha,
  +            "commit": sha,
               "author_name": author.name,
               "author_email": author.email,
               "date": author.date.toString(),
  
positive.code:     }
    }
  
    GitObject([this._sha, this.data]);
  
    // The type of git object.
    String type;
    dynamic data;
    String _sha;
  
    String toString() => data.toString();
  }
  
negative.code:   }
  
    String toString() {
      String str = "commit " + sha + "\n";
      str += "Author: " + author.name + " <" + author.email + ">\n";
      str += "Date:  " + author.date.toString() + "\n\n";
      str += _message;
  