Function import_stream 

pub async fn import_stream<S, R>(
    store: &S,
    header: &ExportHeader,
    mode: ImportMode,
    records: R,
) -> Result<u64, StoreError>
where
    S: NamespaceStore,
    R: Stream<Item = Result<ExportRecord, StoreError>>,

Import a record stream (such as an ExportStream) taken under header; the number of records imported. Records carry their partition, so one stream may restore several partitions.