Single element willLeave animation

Hello, I'm trying to get my head around this tool, it looks very promising, specially for collections of elements, but when it comes to animate a single element in & out (specially out) I can't find any example on how it should be implemented. TransitionMotion seems to be meant for with multiple items, I suppose that you can use it just with one, and provably is trivial, but I can't really make it work, does anyone can point me to a plain example with animation in & out for a single object? Thank you very much!