Say I have an argument with the name 'foo-bar'.  Argparse accepts and parses arguments, but Namespace does not allow me to access the value.

Yes, I can use getattr or Namespace.__dict__.  But that's ugly.
Yes, I can change the name of the argument, but that's not what I want in my help output.

I think it should either:
- Collapse names to valid python identifiers (optparse did this).
- Namespace should act like an object and dict.