code: function collectForKey(edges, object, k) {
  
    if (!(k in object))
      return;
  
    if (object[k] instanceof Set)
      object[k].forEach(edgeData => edges.push(edgeData.key));
    else
      edges.push(object[k].key);
  
    return;
  }
docs: Function collecting edges from the given object at given key.
  
  @param  {array}  edges  - Edges array to populate.
  @param  {object} object - Target object.
  @param  {mixed}  k      - Neighbor key.
  @return {array}         - The found edges.