var data = JSON.parse(value),
 lookup = {},
 result =[];
for (var item, i = 0; item = data[i++];) {
 var code = item.labels.grpc_code;
 if (!(code in lookup)) {
  lookup[code] = 1;
  result.push({ "{#GRPC.CODE}": code});
}
}
return JSON.stringify(result);