Constant EMPTY_VARIANT_METADATA_BYTES 

pub const EMPTY_VARIANT_METADATA_BYTES: &[u8];

The canonical byte slice corresponding to an empty metadata dictionary.

let mut metadata_builder = WritableMetadataBuilder::default();
metadata_builder.finish();
let metadata_bytes = metadata_builder.into_inner();
assert_eq!(&metadata_bytes, EMPTY_VARIANT_METADATA_BYTES);