code: function(expression) {
  			var pastedExpression = new Expression();
  			var key = this._getKey();
  
  			pastedExpression.fromJson(json.parse(localStorage[key]));
  			var newExpression;
  			if (expression) {
  				var expressionClone = new Expression({
  					operator : 'and',
  					expressionList : [expression, pastedExpression]
  				}).toJson();
  				//converting the same instance
  				expression.fromJson(expressionClone);
  				newExpression = expression;
  			} else {
  				newExpression = pastedExpression;
  			}
  
  			var parentBuilder = this.get('filterBuilder');
  
  			parentBuilder.set('expression', newExpression, true /* preventChange Undo State
  			 * */);
  		}
docs: Pastes the copied expression in the same level as the one provided and returns the new Expression If null is provided then it just returns the pasted expression.