var lookup = {},
    result = [];

JSON.parse(value).forEach(function (item) {
    var grpc_method = item.labels.grpc_method;
    if (!(lookup[grpc_method])) {
        lookup[grpc_method] = 1;
        result.push({ "{#GRPC_METHOD}": grpc_method });
    }
})

return JSON.stringify(result);