Hey!

Really loving ArrowJS - super easy to work with :)

One issue I have found is no way to "un watch". Take for example:

• You have some component with an onMount. When mounted you setup a watch on some reactive variable.
• When the component get's disposed of, that watch keeps running.

It would be really helpful if the watch returned some sort of reference which we could then remove on unmount.

A common time this happens is with multi-page apps. When spanning between pages, elements are constantly getting added and removed from the dom. After a bit you just have a bunch of old watch's sitting out there.

Any suggestions are appreciated!
Thanks!