The --xml-dir argument's help string states "Defaults to: {XML_DIR}". However, it sets default=None. Because it expects an argument (type=str), if the user runs python -m ingest.ingest --xml-dir without specifying a path, argparse will throw an error. If the user doesn't pass the flag at all, it falls back to None and runs the HTML ingestion instead.
The --xml-dir argument's help string states "Defaults to: {XML_DIR}". However, it sets default=None. Because it expects an argument (type=str), if the user runs python -m ingest.ingest --xml-dir without specifying a path, argparse will throw an error. If the user doesn't pass the flag at all, it falls back to None and runs the HTML ingestion instead.