be a stylesheet. It
will be injected to the scope of the animated node in the `setup` function. The node is initially
invisible with `opacity: 0`, and you can transition it to an "opened" state by passing
`{opened: true}` to the `go` function.

All nodes being animated will get the class `my-transition` added in the `setup` function.
Additionally, the class `my-transition-<transitionType>` will be applied. You can use the
`transitionType` attribute to implement several different behaviors with the same
`<co