func (iter *Iter) Timeout() bool {
	iter.m.Lock()
	result := iter.timedout
	iter.m.Unlock()
	return result
}
func (iter *Iter) Timeout() bool {
	iter.m.Lock()
	result := iter.timedout
	iter.m.Unlock()
	return result
}
// Timeout returns true if Next returned false due to a timeout of
// a tailable cursor. In those cases, Next may be called again to continue
// the iteration at the previous cursor position.