def METHOD_NAME(parser):
    # add ordinary flags (NOT backed by an environment variable)
    # in the future, it would probably be more ergonomic to assume that the
    # current working directory is the enzo-e build directory when this flag is
    # not specified (and we may want to try parsing CMakeCache.txt)
    parser.addoption(
        "--build-dir", action = 'store', default = None,
        help = ("points to the build-directory where the target enzo-e binary "
                "was built (that binary has the path: BUILD_DIR/bin/enzo-e). "
                "The path to the charmrun launcher will be inferred from the "
                "BUILD_DIR/CMakeCache.txt file, but can be overwritten by the "
                "--charm flag or the CHARM_PATH environment variable. Be "
                "aware that problems can theoretically arise if you do "
                "something to alter the build system's state after a build "
                "without rebuilding enzo-e (CMakeCache.txt may no longer be "
                "valid for the binary). When this flag isn't specified, the "
                "test-driver assumes that the enzo-e binary is located at "
                f"{_root_dir}/build/bin/enzo-e, but does not try to infer "
                "charmrun's location from CMakeCache.txt.")
    )
    # introduce flags that fall back to values specified in an env variable
    # (these flags primarily exist for backwards compatability)
    for flag, par in _CONFIG_OPTIONS.items():
        kwargs = par.other_argparse_kwargs.copy() # don't mutate the original
        kwargs["help"] = (f"{par.help} If not specified, the program tries to "
                          f"use the value set by {par.env_var}")
        kwargs["default"] = None
        if kwargs.get('action', 'store') in ['store_true', 'store_false']:
            raise RuntimeError(
                "for a flag backed by an environment variable, the argparse "
                "kwargs can't set 'action' to 'store_true' or 'store_false'.")
        parser.addoption(flag, **kwargs)