# parser.add_argument("--str", default="test", help="100%%")
#
Traceback (most recent call last):
  File "/Users/aprengere/Dev/cpython/Lib/argparse.py", line 1810, in _check_help
    formatter._expand_help(action)
    ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/Users/aprengere/Dev/cpython/Lib/argparse.py", line 712, in _expand_help
    raise ValueError(f"invalid format specifier in: {help_string!r}")
ValueError: invalid format specifier in: '100%%'

       if '%' in result:
            raise ValueError(f"invalid format specifier in: {help_string!r}")