def _convert_python_version(value):
    # type: (str) -> Tuple[Tuple[int, ...], Optional[str]]
    """
    Convert a version string like "3", "37", or "3.7.3" into a tuple of ints.

    :return: A 2-tuple (version_info, error_msg), where `error_msg` is
        non-None if and only if there was a parsing error.
    """
    if not value:
        # The empty string is the same as not providing a value.
        return (None, None)

    parts = value.split('.')
    if len(parts) > 3:
        return ((), 'at most three version parts are allowed')

    if len(parts) == 1:
        # Then we are in the case of "3" or "37".
        value = parts[0]
        if len(value) > 1:
            parts = [value[0], value[1:]]

    try:
        version_info = tuple(int(part) for part in parts)
    except ValueError:
        return ((), 'each version part must be an integer')

    return (version_info, None)

    Convert a version string like "3", "37", or "3.7.3" into a tuple of ints.

    :return: A 2-tuple (version_info, error_msg), where `error_msg` is
        non-None if and only if there was a parsing error.
    
product/gradle-plugin/src/main/python/pip/_internal/cli/cmdoptions.py