anchor.diff:  
   typedef bool _CheckExceptionFn(exception);
   
  +@deprecated
   class ExpectException implements Exception {
     ExpectException(this.message);
     String toString() => message;
  
positive.code:   }
  
    // Unconditional failure.
    static void fail(String msg) {
      _fail("Expect.fail('$msg')");
    }
  
negative.code:    * Checks that every element of [expected] is also in [actual], and that
     * every element of [actual] is also in [expected].
     */
    @deprecated
    static void setEquals(Iterable expected,
                          Iterable actual,
                          [String reason = null]) {
  