def validate_package_type(package_type):
    """Validate PackageType for Lambda Function.
    :param package_type: The PackageType specified in the Function.
    :return: The provided package type if it is valid.
    Property: Function.PackageType
    """

    PACKAGE_TYPES = ["Image", "Zip"]

    if package_type not in PACKAGE_TYPES:
        raise ValueError(
            "Lambda Function PackageType must be one of: {}".format(
                ", ".join(PACKAGE_TYPES)
            )
        )
    return package_type