Possible to create a |diff custom pipe?

I pinged @gdi2290 on Twitter to see if he has any insight into whether it is possible to get access in Angular2's pipes to get both the last and next value of whatever is being piped. 

If we can actually get at both the last and next value of pipes then we could create a custom pipe that uses jsdiff's .convertToXML() to show diffs of objects/properties over time.
