code: function(model) {
        if (!model) {
          this.__cache = {};
          _.each(this.getTrackedModels(), function(model) {
            if (model) {
              this.__updateCache(model);
            }
          }, this);
        } else {
          this.__cache[model.cid] = this.__generateHashValue(model);
        }
      }
docs: Updates the form model's snapshot of the model's attributes to use later
  @param model {Backbone.Model instance} the object model
  @param [cache=this.__cache] {Object} if passed an object (can be empty), this method will fill
  this cache object instead of this form model's __cache field
  @private
  @method __updateCache