How to use the d3-collection.map function in d3-collection

constructor (dispatcher, labelType, currency, txLabelType) {
    super()
    this.currency = currency
    this.dispatcher = dispatcher
    this.labelType = labelType
    this.txLabelType = txLabelType
    // nodes of the graph
    this.entityNodes = map()
    this.addressNodes = map()
    // ids of addresses/entities present in graph
    this.references = {address: map(), entity: map()}
    this.adding = set()
    this.selectedNode = null
    this.highlightedNodes = []
    this.layers = []
    this.transform = {k: 1, x: 0, y: 0, dx: 0, dy: 0}
    this.colorMapCategories = map()
    this.colorMapTags = map()
    let colorGen = (map, type) => (k) => {
      if (!k) return defaultColor[type]
      let color = map.get(k)
      if (color === undefined) {
        color = colorScale(map.size())
        map.set(k, color.toString())

super()
    this.currency = currency
    this.dispatcher = dispatcher
    this.labelType = labelType
    this.txLabelType = txLabelType
    // nodes of the graph
    this.entityNodes = map()
    this.addressNodes = map()
    // ids of addresses/entities present in graph
    this.references = {address: map(), entity: map()}
    this.adding = set()
    this.selectedNode = null
    this.highlightedNodes = []
    this.layers = []
    this.transform = {k: 1, x: 0, y: 0, dx: 0, dy: 0}
    this.colorMapCategories = map()
    this.colorMapTags = map()
    let colorGen = (map, type) => (k) => {
      if (!k) return defaultColor[type]
      let color = map.get(k)
      if (color === undefined) {
        color = colorScale(map.size())
        map.set(k, color.toString())
      }
      let c = hsl(color)
      c.l = c.l * lightnessFactor[type]
      return c
    }
    this.colors =
      {
        'entity': {
          categories: colorGen(this.colorMapCategories, 'entity'),

constructor () {
    this.addresses = map()
    this.entities = map()
    this.outgoingLinks = map()
    this.notesStore = map()
    this.tagsStore = map()
  }
  /**

constructor () {
    this.addresses = map()
    this.entities = map()
    this.outgoingLinks = map()
    this.notesStore = map()
    this.tagsStore = map()
  }
  /**

constructor () {
    this.addresses = map()
    this.entities = map()
    this.outgoingLinks = map()
    this.notesStore = map()
    this.tagsStore = map()
  }
  /**

constructor (paper, opts, defaults) {
        var transitions = map(),
            options = {};
        forEach(opts, (o, key) => {
            if (isObject(o)) transitions.set(key, o);
            else options[key] = o;
        });
        super(paper, options, defaults);
        var scope = this.$scope;
        scope.transitions = map();
        transitions.each((o, key) => {
            scope.transitions.set(key, scope.$new().$extend(o));
        });
    }
    /**

constructor (id) {
    super()
    this.id = id
    this.nodes = map()
  }
  serialize () {

constructor ($location, $q, $http, $log, $timeout, context) {
        this.$location = $location;
        this.$q = $q;
        this.$http = $http;
        this.$log = $log;
        this.$timeout = $timeout;
        this.apis = map();
        this.context = context;
    }

initOutgoing (id, keyspace) {
    if (typeof id !== 'string' && typeof id !== 'number') {
      throw new Error('id is not string')
    }
    let outgoing = this.outgoingLinks.get(prefix(keyspace, id))
    if (!outgoing) {
      outgoing = map()
      this.outgoingLinks.set(prefix(keyspace, id), outgoing)
    }
    return outgoing
  }
  linkOutgoing (source, target, keyspace, data) {

export default function Digraph () {
  this._nodes = []
  this._edges = []
  this._dummyNodes = map()
}