We need to be careful about when or where _negative_number_match is changed.
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We basically do:
parser = argparse.ArgumentParser(...)
parser._negative_number_matcher = re.compile(r'^-.+$')
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This changes the value for the parser itself, but not for the groups (_optionals, _positionals) or any subparsers. The code takes special care to make sure that the related property: _has_negative_number_optionals is properly shared among all these ActionContainers.