code: function (gruntfileContent) {
    var defaultGruntfilePath = path.join(__dirname, 'default-gruntfile.js');
    gruntfileContent = gruntfileContent || fs.readFileSync(defaultGruntfilePath);
    this.gruntfile = new Tree(gruntfileContent.toString());
  }
docs: A class managing the edition of the project Gruntfile content. Editing the
  Gruntfile using this class allow easier Generator composability as they can
  work and add parts to the same Gruntfile without having to parse the
  Gruntfile AST themselves.
  @constructor
  @param  {String} gruntfileContent - The actual `Gruntfile.js` content