Usage of model-not-found delegate in Catfish

gistfile1.js

var modelNotFoundDelegate = require('../lib/model-not-found-delegate')
  , modelNotFound = modelNotFoundDelegate(router, collection, debug)

router.route('sections/:id/layout(/)', 'editLayout', function (id) {
  collection.fetch(
    { update: true
    , success: function () {
      if (modelNotFound(id)) return false
      var view = new LayoutView({ model: collection.get(id) })
      router.render(view, 'Section Layout')
    }
  })
})