code: function MapObjectRW(ktype, vtype) {
      this.ktype = ktype;
      this.vtype = vtype;
  
      if (this.vtype.rw.width) {
          this.poolByteLength = this.mapVarFixbyteLength;
      }
  
      bufrw.Base.call(this);
  }
docs: RW a thrift map to an Object ktype:1 vtype:1 length:4 (k... v...){length}