This also fails if you're using `expressionContext`. Both values will be undefined, the values under that key have a numbered index (which corresponds to the index of the associated function in the expression).    ![screenshot 2019-03-05 13 25 03](https://user-images.githubusercontent.com/404731/53835249-39b7fe00-3f4a-11e9-9718-97c1999d58ad.png)  