anchor.diff:      => length > 0 ? new String(this.sequence().terminal(length)) : String.instance("");
   
     //  shared actual native [String,String] slice(Integer index);
  -  Sequence slice([$dart$core.int length]) {
  +  Tuple slice([$dart$core.int length]) {
       var its = this.sequence().slice(length);
  -    return new ArraySequence(new Array._withList([
  +    return new Tuple.$withList([
           new String(its.getFromFirst(0)),
  -        new String(its.getFromFirst(1))]));
  -  }
  -
  +        new String(its.getFromFirst(1))]);
  +  }
  +
  +  
     //  shared actual native Integer size;
     @$dart$core.override
     $dart$core.int get size => _value.runes.length;
  
positive.code:   Integer get successor => new Integer(this._value + 1);
  
    // Comparable
    Comparison compare([Float other])
        =>  _value < other._value ? smaller : (_value > other._value ? larger : equal);
  
    //Comparison compare(Integer other);
  
negative.code:     0xa620, 0xa8d0, 0xa900, 0xa9d0, 0xaa50, 0xabf0, 0xff10,
      0x104a0, 0x11066, 0x110f0, 0x11136, 0x111d0, 0x116c0]);
  
  class Character implements Comparable, Enumerable {
    $dart$core.int _value;
  
    Character(Character character) {
  