pub trait HeaderMetadata<Block: BlockT> {
    type Error: Error;
    // Required methods
    fn header_metadata(
        &self,
        hash: Block::Hash,
    ) -> Result<CachedHeaderMetadata<Block>, Self::Error>;
    fn insert_header_metadata(
        &self,
        hash: Block::Hash,
        header_metadata: CachedHeaderMetadata<Block>,
    );
    fn remove_header_metadata(&self, hash: Block::Hash);
}Expand description
Handles header metadata: hash, number, parent hash, etc.