code: func (b *BufferedSeriesIterator) Reset(it SeriesIterator) {
  	b.it = it
  	b.lastTime = math.MinInt64
  	b.ok = true
  	b.buf.reset()
  	b.buf.delta = b.delta
  	it.Next()
  }
docs: // Reset re-uses the buffer with a new iterator, resetting the buffered time
  // delta to its original value.