index.js
function Link(fromId, toId, data, id) {
  this.fromId = fromId;
  this.toId = toId;
  this.data = data;
  this.id = id;
}
function Link(fromId, toId, data, id) {
  this.fromId = fromId;
  this.toId = toId;
  this.data = data;
  this.id = id;
}
function Link ( fromId , toId , data , id ) { this . fromId = fromId ; this . toId = toId ; this . data = data ; this . id = id ; }
Internal structure to represent links;
Internal structure to represent links ;