code: function FlatToNested(config) {
      this.config = config = config || {};
      this.config.id = config.id || 'id';
      this.config.parent = config.parent || 'parent';
      this.config.children = config.children || 'children';
      this.config.options = config.options || { deleteParent: true };
    }
docs: Create a new FlatToNested object.
  
  @constructor
  @param {object} config The configuration object.