anchor.diff:      testInvocations(m, m2);
     }));
   
  -  toString() => new _Equals(equals = getWrappedObject((m2) {
  +  // dartanalyzer complains if this method is named `toString()`, since, if it
  +  // truly overrides Object's `toString()`, it should return a String.
  +  asString() => new _Equals(equals = getWrappedObject((m2) {
       testInvocations(TO_STRING_INVOCATION, m2);
     }));
   }
  
positive.code:     expect.putIfAbsent(val, func0).equals.putIfAbsent(val, func0);
      expect.remove(val).equals.remove(val);
      expect.values.equals.values;
      expect.toString().equals.toString();
    }
  
    // Runs tests of Set behavior.
  
negative.code:     expect.toList(growable: true).equals.toList(growable: true);
      expect.toList(growable: false).equals.toList(growable: false);
      expect.toSet().equals.toSet();
      expect.asString().equals.toString();
      expect.where(func1).equals.where(func1);
    }
  
  