* assign types to properties
  - modifications to types don't commute the same way
  - optimize this to simplify the transform function
  - types:
    - dependencies: set of uuids
    - annotations: set of annotations (incl timestamps for uniqueness)
    - tags: set of tags
  - idea: Update takes a dotted path for property; store everything as a map
    e.g., {uuid: true}, {timestamp: annotation}, {tag: true}; keep the
    set-to-null-to-delete to remove
* add HTTP API
* implement snapshot requests
* implement backups
* implement client-side encryption
* design expiration
  - need to be sure that create / delete operations don't get reversed
* cli tools
* prop testing for DB modifications