public Iterator4 iterator() {
   return _classes.valuesIterator();
 }
 public String toString() {
   return "CustomClassRepository(classes: " + _classes.size() + ")";
 }
 private CustomClass defineClass(CustomClass klass) {
   _classes.put(klass.getName(), klass);
   return klass;
 }
 private void assertNotDefined(String className) {
   if (_classes.containsKey(className)) {
     throw new IllegalArgumentException("Class '" + className + "' already defined.");
   }
 }
 public CustomClass forName(String className) {
   return (CustomClass) _classes.get(className);
 }