def mac_platforms(version=None, arch=None):
    # type: (Optional[MacVersion], Optional[str]) -> Iterator[str]
    """
    Yields the platform tags for a macOS system.

    The `version` parameter is a two-item tuple specifying the macOS version to
    generate platform tags for. The `arch` parameter is the CPU architecture to
    generate platform tags for. Both parameters default to the appropriate value
    for the current system.
    """
    version_str, _, cpu_arch = platform.mac_ver()  # type: ignore
    if version is None:
        version = cast("MacVersion", tuple(map(int, version_str.split(".")[:2])))
    else:
        version = version
    if arch is None:
        arch = _mac_arch(cpu_arch)
    else:
        arch = arch
    for minor_version in range(version[1], -1, -1):
        compat_version = version[0], minor_version
        binary_formats = _mac_binary_formats(compat_version, arch)
        for binary_format in binary_formats:
            yield "macosx_{major}_{minor}_{binary_format}".format(
                major=compat_version[0],
                minor=compat_version[1],
                binary_format=binary_format,
            )

    Yields the platform tags for a macOS system.

    The `version` parameter is a two-item tuple specifying the macOS version to
    generate platform tags for. The `arch` parameter is the CPU architecture to
    generate platform tags for. Both parameters default to the appropriate value
    for the current system.
    
src/pkg_resources/_vendor/packaging/tags.py