======state======
<code>
state := <todo|in-progress|blocked|done>
</code>
I theory this can contain any UTF-8 encoded string but the four strings:
  * ''todo'' - Task is not yet started.
  * ''in-progress'' - Task has been started.
  * ''blocked'' - Task has been started but is currently blocked from further progress.
  * ''done'' - Task is finished.

More states may be added in the future.