code: func (it *Iterator) SeekForPrev(key []byte) (found bool) {
  	var prev, next *node
  	prev, next, found = it.seekForBaseSplice(key)
  
  	var present bool
  	if found {
  		present = it.setNode(next, true)
  	} else {
  		present = it.setNode(prev, true)
  	}
  
  	return found && present
  }
docs: // SeekForPrev searches for the record with the given key. If it is present in
  // the skiplist, then SeekForPrev positions the iterator on that record and
  // returns true. If the record is not present, then SeekForPrev positions the
  // iterator on the preceding node (if it exists) and returns false.