Investigate subparsers with no arguments

[jmgate]

trafficstars

Description

I suspect we may have a bug in that reverse_argparse likely doesn't correctly handle the case of a subparser with no argument, e.g., when the subcommand is simply mapped to a function. Need to

• [ ] Develop one or more test cases to prove the point.
• [ ] Fix the unparsing of nested parsers for such situations.