Perspective: Fallback to binding value in Transform

v8.1rc1

How can I fall back to the previous value when using a transform?
For example,

  1. if you have a single transform, fall back to the binding value.
  2. if you have chained transforms, fall back to the previous transform, or to the binding value if it’s the first transform in the chain

Below, I want to fall back to the value of the tag, if it’s not false or true (as in this case, it’s going to be a string value already)
image

For now, I’ve reverted back to using the Expression transform and a case statement.

Does having {value} in your fallback like In the image not work?