You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: optics.go
    path of file: ./repos/photoprism/pkg/clusters
    
    the code of the file until where you have to start completion: package clusters

import (
	"math"
	"sync"
)

type steepDownArea struct {
	start, end int
	mib        float64
}

type clusterJob struct {
	a, b, n int
}

type opticsClusterer struct {
	minpts, workers int
	eps, xi, x      float64

	distance DistFunc

	// slice
    
func (c *opticsClusterer) update(p int, d float64, l int, r []int, q *priorityQueue) {
	for i := 0; i < l; i++ {
		if !c.v[r[i]] {
			m := math.Max(d, c.distance(c.d[p], c.d[r[i]]))

			if c.re[r[i]] == nil {
				item := &pItem{
					v: r[i],
					p: m,
				}

				c.re[r[i]] = item

				q.Push(item)
			} else if m < c.re[r[i]].p {
				q.Update(c.re[r[i]], c.re[r[i]].v, m)
			}
		}
	}
}