code: function (callback) {
          if(this.masterDelta && !callback({}, cloneDeep(this.masterDelta))) {
              return undefined;
          }
          this._walkSettingsHelper(this.tree, 0, [], callback, [false]);
      }
docs: Iterates over all the setting sections in the YCB file, calling the
  callback for each section.
  @method walkSettings
  @param callback {function(settings, config)}
  @param callback.settings {object} the condition under which section will be used
  @param callback.config {object} the configuration in the section
  @param callback.return {boolean} if the callback returns false, then walking is stopped
  @return {nothing} results returned via callback