export class DefaultRenderer implements Renderer {
  underMeanColor: string
  overMeanColor: string

   constructor(underMeanColor = '#0000ff', overMeanColor = '#ff0000') {
     this.underMeanColor = underMeanColor
     this.overMeanColor = overMeanColor
     super() 
  } 
  
    public render( { count, position }: Cluster, stats: ClusterStats, map: google.maps.Map): Marker {
    // change color if this cluster has more markers than the mean cluster
    const color =
      count > Math.max(10, stats.clusters.markers.mean) ? this.overMeanColor : this.underMeanColor;
   
   // ...
}