anchor.diff:  }
   
   class ClassB implements B {
  +  // for the record, these do not correspond to B's constructors - see Ch. 8.4
     factory B(a, b, [c = 0]) {}
     factory B.c() {}
  -  ClassB(a, b, c) {}
  +  
  +  // these do correspond to B's constructors
  +  ClassB(a, b, [c]) {}
     ClassB.C() {}
   }
   
  -class Class implements C, E {
  -  Class() {}
  +class ClassC implements C, E {
  +  ClassC() {}
   }
   
   main() {
     new A();
     new B(1, 2, 3);
  -  new Class();
  +  new ClassC();
   }
  
positive.code:  *   variableDeclaration ';'
   * ;
   * @description Checks that valid interface declarations don't produce a compile-time error
   * @author msyabro
   * @reviewer kaigorodov
   */
  
  interface A default ClassA {
  
negative.code:   set something(something);
  }
  
  interface B extends A default ClassB {
    B(a, b, [c = 0]);
    B.C();
  
  