Function seek_stream 

pub(super) fn seek_stream<'a, C, T>(
    map: &'a Arc<Map>,
    dir: Direction,
    from: Option<&[u8]>,
) -> impl Stream<Item = Result<T>> + Send + use<'a, C, T>
where
    C: From<State<'a>> + Stream<Item = Result<T>> + Send,

Builds a forward or reverse map stream from an optional raw seek key.

A block-cache probe selects inline iteration when the initial seek is cached; otherwise the seek runs on the engine’s blocking pool. The projection type determines whether each item contains a key alone or a key-value pair.