+; TODO optional text wrap
+; TODO write
+; TODO caching (use cache by default, unless explicitly asked for update)
+; TODO timeline limits
+; TODO user-defined feed sets (a la twitter lists)
+; TODO feed set operations
+; TODO timeline as a result of a query (feed set op + filter expressions)
+; TODO named timelines
+; TODO CLI params
+; TODO config files
+; TODO parse mentions:
+; - @<source.nick source.url> | @<source.url>
+; TODO highlight mentions
+; TODO filter on mentions
+; TODO highlight hashtags
+; TODO filter on hashtags
+; TODO hashtags as channels? initial hashtag special?
+; TODO query language
+; TODO concurrency
+; TODO console logger colors by level ('error)
+; TODO file logger ('debug)
+; TODO commands:
+; - r | read
+; - see timeline ops above
+; - w | write
+; - arg or stdin
+; - nick expand to URI
+; - q | query
+; - see timeline ops above
+; - see hashtag and channels above
+; - d | download
+; - u | upload
+; - calls user-configured command to upload user's own feed file to their server
+; TODO user-agent format: <client>/<version> (+<source.url>; @<source.nick>)
+; - requires configurability
+; - ref: https://twtxt.readthedocs.io/en/latest/user/discoverability.html
+