anchor.diff:  
     }
     writeDouble(value) {
  +    _ensureSpace(9);
       writeType(_DOUBLE);
       throw "not implemented";
       //buf.setFloat64(bufPos,value,  Endianness.HOST_ENDIAN);
       //bufPos+=8; 
     } 
     writeBool(value) {
  +    _ensureSpace(2);
       writeType(_BOOL);
       buf[bufPos++]= value?1:0;
     }
     writeTypeAndLength(type, length) {
  -    buf[bufPos++]=type;
  +    buf[bufPos++]=type&0x1F;
       if (length<=255) {
         buf[bufPos++] = length;
         return;
  
positive.code:     }  
    } 
    writeList(value, type, subtype) {
      writeTypeAndLength(_LIST_GENERIC, value.length);
      for (int i=0; i<value.length; i++)
        writeGeneric(value[i], type, subtype);
    }
    writeListInt(value) {
      writeTypeAndLength(_LIST_INT, value.length);
      
      for (int i=0; i<value.length; i++)
        writeInt(value[i]);
    }
    writeListString(value) {
      writeTypeAndLength(_LIST_STRING, value.length);
      
      for (int i=0; i<value.length; i++)
        writeString(value[i]);
    }
    writeMap(value, type, subtype) {
      writeTypeAndLength(_MAP_GENERIC, value.length);
      value.forEach((k,v){ writeString(k); writeGeneric(v, type, subtype); });
    }
    writeGeneric(value, type, subtype) {
      if (value==null) {
        buf[bufPos++]=0; // type=0 is null
        return;
      }
  
negative.code: 
  class Pigeonson {
  
    var buf;
    int bufPos=0;
    int bufLength;
    serialize(PigeonStruct map) {
      bufLength=1024;
      buf=new Uint8List(bufLength);
      writePigeon(map, map.nameSet.type);
      return new Uint8List.view(buf.buffer, 0, bufPos);
    }
    _ensureSpace(extraLength) {
      if (bufPos+extraLength>bufLength) {
        var newBuf=new Uint8List(bufLength*2);
        newBuf.setRange(0, bufPos, buf, 0);
        buf=newBuf;
        bufLength=newBuf.length;
      }
    }
    writePigeon(obj, objtype) {
      _ensureSpace(8);
      writeType(_PIGEON);
      var slotTypes=obj.nameSet.pigeonsonSlotTypes;
      var len=obj.nameSet.length;
  