Function record_leaf 

pub fn record_leaf(
    coll: &str,
    id: &str,
    data: &Value,
    valid_from: Option<&str>,
    valid_to: Option<&str>,
) -> Result<Digest32, String>

One live document, as logical content.

seq, ts, prev and the object hash are all deliberately absent: they describe how and when this state was arrived at, which is history’s job.