anchor.diff:    Expect.isTrue(set.containsAll(set));
   
     // Test Set.map.
  -  testMap(int val) {
  -    return val * val;
  +  testMap(Object val) {
  +    return (val as int) * (val as int);
     }
   
     Set mapped = set.map(testMap).toSet();
  
positive.code:   Expect.isTrue(set.containsAll(filtered));
  
    // Test Set.every.
    testEvery(int val) {
      return (val < 10);
    }
  
    Expect.isTrue(set.every(testEvery));
  
negative.code: 
    // Test Set.forEach.
    int sum = 0;
    testForEach(Object val) {
      sum += ((val as int) + 1);
    }
  
    set.forEach(testForEach);
  