anchor.diff:    Object operator>>>(v1, v2) => null;  //# arg2: compile-time error
     Object operator>>>([v1]) => null;  //# argOpt: compile-time error
     Object operator>>>({v1}) => null;  //# argNam: compile-time error
  -  // The operator must not be async* or sync*.
  -  Stream<Object> operator>>>(v) async* {}  //# asyncstar: compile-time error
  -  Iterable<Object> operator>>>(v) sync* {}  //# syncstar: compile-time error
   }
   
   /// Class with noSuchMethod and no `>>>` operator.
   class NSM {
  -  dynamic noSuchMethod(Invocation i) {
  +  dynamic noSuchMethod(Invocation invocation) {
       return invocation;
     }
   }
  
positive.code:   Expect.isFalse(invocation.isAccessor);
    Expect.equals(#>>>, invocation.memberName);
    Expect.equals(1, invocation.positionalArguments.length);
    Expect.identical(c2, invocation.positionalArguments[1]);
    Expect.equals(0, invocation.namedArguments.length);
  
    invocation = (nsm >>>= c2);
  
negative.code: 
  /// Class with an `async` implementation of `operator >>>`
  class Async {
    Future<C> operator >>>(C value) async => value;
  }
  
  /// Class with an `async*` implementation of `operator >>>`
  class AsyncStar {
    Stream<C> operator >>>(C value) async* {
      yield value;
    }
  }
  
  /// Class with a `sync*` implementation of `operator >>>`
  class SyncStar {
    Iterable<C> operator >>>(C value) sync* {
      yield value;
    }
  }
  
  /// Helper class to record precedence and associativity of operators.
  class Assoc {
    final String ops;
    Assoc(this.ops);
    Assoc operator ~() => Assoc("(~${this})");
    Assoc operator +(Assoc other) => Assoc("(${this}+$other)");
    Assoc operator /(Assoc other) => Assoc("(${this}/$other)");
    Assoc operator &(Assoc other) => Assoc("(${this}&$other)");
    Assoc operator |(Assoc other) => Assoc("(${this}|$other)");
    Assoc operator ^(Assoc other) => Assoc("(${this}^$other)");
    Assoc operator >(Assoc other) => Assoc("(${this}>$other)");
    Assoc operator >>(Assoc other) => Assoc("(${this}>>$other)");
    Assoc operator >>>(Assoc other) => Assoc("(${this}>>>$other)");
    Assoc operator <(Assoc other) => Assoc("(${this}<$other)");
    Assoc operator >=(Assoc other) => Assoc("(${this}>=$other)");
    Assoc operator <=(Assoc other) => Assoc("(${this}<=$other)");
    String toString() => ops;
  }
  