func (c *concreteSeriesIterator) At() (t int64, v float64) {
	s := c.series.samples[c.cur]
	return s.Timestamp, s.Value
}
func (c *concreteSeriesIterator) At() (t int64, v float64) {
	s := c.series.samples[c.cur]
	return s.Timestamp, s.Value
}
func ( c * concreteSeriesIterator ) At ( ) ( t int64 , v float64 ) { s := c . series . samples [ c . cur ] return s . Timestamp , s . Value }
// At implements storage.SeriesIterator.
At implements storage . SeriesIterator .