def bigger_version(version_string_a, version_string_b):
    """Returns the bigger version of two version strings."""
    major_a, minor_a, patch_a = parse_version_string(version_string_a)
    major_b, minor_b, patch_b = parse_version_string(version_string_b)

    if major_a > major_b:
        return version_string_a
    elif major_a == major_b and minor_a > minor_b:
        return version_string_a
    elif major_a == major_b and minor_a == minor_b and patch_a > patch_b:
        return version_string_a
    return version_string_b
Returns the bigger version of two version strings.