TODO

* <struct:toc/> copies hyperlinks from the header to the ToC, what is wrong.

* Should --preload fail if there is no such asset?

* Correct error on RDF syntax error in an asset.

* .translate() in command_line/command.py

* https://pypi.org/project/executor/ for spawning processes?

* to make processing of RDF deterministic:
  https://github.com/koo5/univar/blob/master/pyin/ordered_rdflib_store.py

* Don't download URL twice if they differ only in #ID in the end of the URL.

* How to "import" in Python through the network:
  https://docs.python.org/3/reference/import.html#replacing-the-standard-import-system

* --before cmdline option to set order of precedences

* ScriptsIterator should remember the message with the reason it stopped for.

* Rewrite everything in D programming language, Python is too slow.

* Fast incremental processing of changed XML files (with a server).