@classmethod
def get_role(cls, image_type_id):
    """Get the role played by the image, based on its type."""
    return {cls.KERNEL: 'kernel', cls.RAMDISK: 'ramdisk', cls.DISK: 'root',
        cls.DISK_RAW: 'root', cls.DISK_VHD: 'root', cls.DISK_ISO: 'iso',
        cls.DISK_CONFIGDRIVE: 'configdrive'}.get(image_type_id)
