Removes batches from the pending cache if found in the block store,
        and notifies any observers.

def chain_update(self, block, receipts):
        """Removes batches from the pending cache if found in the block store,
        and notifies any observers.
        """
        with self._lock:
            for batch_id in self._pending.copy():
                if self._batch_committed(batch_id):
                    self._pending.remove(batch_id)
                    self._update_observers(batch_id,
                                           ClientBatchStatus.COMMITTED)