func newAgg(params dist.Params, now time.Time) *agg {
	return &agg{
		params: params,
		rec: Record{
			StartTime: now.In(time.UTC).UnixNano(),
			Merged:    1,
		},
	}
}
newAgg returns an agg that can observe values and write a record.
package data
import (
	"sync"
	"time"
	"github.com/vivint/rothko/dist"
)
type agg struct {
	mu     sync.Mutex
	rec    Record
	params dist.Params
	dist   dist.Dist
}