def validate_license_model(license_model):
    """
    Validate LicenseModel for DBInstance
    Property: DBInstance.LicenseModel
    """

    VALID_LICENSE_MODELS = (
        "license-included",
        "bring-your-own-license",
        "general-public-license",
        "postgresql-license",
    )

    if license_model not in VALID_LICENSE_MODELS:
        raise ValueError(
            "DBInstance LicenseModel must be one of: %s"
            % ", ".join(VALID_LICENSE_MODELS)
        )
    return license_model