Function compact_with_iterator 

pub async fn compact_with_iterator<K: Key, V: Value, W: WriteBytes + Send>(
    iterator: impl LayerIterator<K, V>,
    num_items: usize,
    writer: W,
    block_size: u64,
    yielder: Option<impl Yielder>,
) -> Result<u64, Error>

Writes the items yielded by the iterator into the supplied object.