demo/amd/rjs/output/unified/marionette-build.js
function(options, key) {
        if (options.behaviorClass) {
          return options.behaviorClass;
        }
  
        // Get behavior class can be either a flat object or a method
        return Marionette._getValue(Behaviors.behaviorsLookup, this, [options, key])[key];
      }
function(options, key) {
        if (options.behaviorClass) {
          return options.behaviorClass;
        }
  
        // Get behavior class can be either a flat object or a method
        return Marionette._getValue(Behaviors.behaviorsLookup, this, [options, key])[key];
      }
Takes care of getting the behavior class given options and a key. If a user passes in options.behaviorClass default to using that. Otherwise delegate the lookup to the users `behaviorsLookup` implementation.