test_selection = parser.add_argument_group("Test selection", "What should the script test")
mutex_group.add_argument(
"--test", "-t", metavar=("A", "B"), type=int, nargs=2, help="Select a specific A and B to run"
)
will display under "Test selection":
--test A, -t A- Select a specific A and B to run (default: None)
will display under "Test selection":