func addMetricPoint(metricPoint metricPoint, field func(metricPoint) float64, timerange api.Timerange, buckets [][]float64) bool {
value := field(metricPoint)
// The index to assign within the array is computed using the timestamp.
// It floors to the nearest index.
index := (metricPoint.Timestamp - timerange.Start()) / timerange.ResolutionMillis()
if index < 0 || index >= int64(timerange.Slots()) {
return false
}
buckets[index] = append(buckets[index], value)
return true
}
