code: func (kf *KeyFormat) Iterator(iterable KVIterable, start, end []byte, reverse ...bool) KVIterator {
  	if len(reverse) > 0 && reverse[0] {
  		return kf.prefix.Iterator(iterable.ReverseIterator, start, end)
  	}
  	return kf.prefix.Iterator(iterable.Iterator, start, end)
  }
docs: // Returns an iterator over the underlying iterable using this KeyFormat's prefix. This is to support proper iteration over the
  // prefix in the presence of nil start or end which requests iteration to the inclusive edges of the domain. An optional
  // argument for reverse can be passed to get reverse iteration.