func (r *sampleRing) iterator() SeriesIterator {
	r.it.r = r
	r.it.i = -1
	return &r.it
}
func (r *sampleRing) iterator() SeriesIterator {
	r.it.r = r
	r.it.i = -1
	return &r.it
}
func ( r * sampleRing ) iterator ( ) SeriesIterator { r . it . r = r r . it . i = - 1 return & r . it }
// Returns the current iterator. Invalidates previously returned iterators.
Returns the current iterator . Invalidates previously returned iterators .