code: private long getLastSequencePushed() {
          if (isPull())
              return -1L;
          if (_lastSequencePushed <= 0L) {
              // If running replicator hasn't updated yet, fetch the checkpointed last sequence:
              String lastSequence = db.lastSequenceWithCheckpointId(remoteCheckpointDocID());
              if (lastSequence != null)
                  _lastSequencePushed = Long.valueOf(lastSequence);
          }
          return _lastSequencePushed;
      }
docs: - (SInt64) lastSequencePushed