There are several use-cases with async actions that involve scheduling:
* we do one action and cancel subsequent actions
* we do one action and subsequent calls wait on the initial call
* we start an action and show a loading state
If you want to wait on subsequent calls you need to store action promises.
[ex][req]
If you just want to cancel subsequent calls, you can keep track of a pending
state in the store. [ex][state]
The advantage of adding the pending state to the store is that we can use that
in the UI:
* disable/hide the pretty print button
* show a progress ui
