pub fn insert(collection: CollectionName, id: Option<u64>, contents: impl Into<Bytes>) -> Self {
                pub fn update(collection: CollectionName, header: Header, contents: impl Into<Bytes>) -> Self {
                pub fn insert(collection: CollectionName, id: Option<u64>, contents: impl Into<Bytes>) -> Self {
                pub fn update(collection: CollectionName, header: Header, contents: impl Into<Bytes>) -> Self {