anchor.diff:      throw IterableElementError.noElement();
     }
   
  -  double lastWhere(bool test(double element), {double orElse()}) {
  +  double lastWhere(bool test(double element), {double orElse()?}) {
       var len = this.length;
       for (var i = len - 1; i >= 0; --i) {
         var element = this[i];
  
positive.code:         offsetInBytes + (index * Uint16List.bytesPerElement), _toUint16(value));
    }
  
    void setRange(int start, int end, Iterable iterable, [int skipCount = 0]) {
      if (iterable is CodeUnits) {
        end = RangeError.checkValidRange(start, end, this.length);
        int length = end - start;
  
negative.code:     throw IterableElementError.noElement();
    }
  
    Float32x4 singleWhere(bool test(Float32x4 element), {Float32x4 orElse()?}) {
      var result = null;
      bool foundMatching = false;
      var len = this.length;
  