diff --git a/aqua/examples/option.aqua b/aqua/examples/option.aqua
new file mode 100644
index 0000000..6d425f8
--- /dev/null
+++ b/aqua/examples/option.aqua
@@ -0,0 +1,8 @@
+service SomeS("test2"):
+    getStr: ?string -> ?string
+    getStr2: string -> string
+
+func useOptional(opt: ?string, ackEm: string -> (), ack: string, ?string -> (), ack2: string, string -> ()) -> string:
+    ackEm("before")
+    ack("first", opt)
+    <- opt!
\ No newline at end of file
diff --git a/package.json b/package.json
index 97edbb3..a96dd76 100644
--- a/package.json
+++ b/package.json
@@ -19,11 +19,12 @@
     "build": "tsc",
     "examples": "node -r ts-node/register src/run-examples.ts",
     "exec": "npm run compile-aqua && node -r ts-node/register src/index.ts",
+    "run": "node -r ts-node/register src/index.ts",
     "compile-aqua": "aqua-cli -i ./aqua/ -o ./src/compiled",
     "compile-aqua:air": "aqua-cli -i ./aqua/ -o ./compiled-air -a"
   },
   "devDependencies": {
-    "@fluencelabs/aqua-cli": "^0.1.2-129",
+    "@fluencelabs/aqua-cli": "^0.1.4-133",
     "@fluencelabs/aqua-lib": "^0.1.3",
     "ts-node": "^9.1.1",
     "typescript": "^4.2.4"
diff --git a/src/compiled/examples/callArrow.ts b/src/compiled/examples/callArrow.ts
index a70ae34..6e141da 100644
--- a/src/compiled/examples/callArrow.ts
+++ b/src/compiled/examples/callArrow.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/complex.ts b/src/compiled/examples/complex.ts
index 17f531c..2292772 100644
--- a/src/compiled/examples/complex.ts
+++ b/src/compiled/examples/complex.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/constants.ts b/src/compiled/examples/constants.ts
index 38afe99..cb7f76c 100644
--- a/src/compiled/examples/constants.ts
+++ b/src/compiled/examples/constants.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/dataAlias.ts b/src/compiled/examples/dataAlias.ts
index 07e6c14..a0ca94a 100644
--- a/src/compiled/examples/dataAlias.ts
+++ b/src/compiled/examples/dataAlias.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/example.ts b/src/compiled/examples/example.ts
index 8ba7aa0..4fc51fb 100644
--- a/src/compiled/examples/example.ts
+++ b/src/compiled/examples/example.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/fldist-sample.ts b/src/compiled/examples/fldist-sample.ts
index 821ef24..08a44fc 100644
--- a/src/compiled/examples/fldist-sample.ts
+++ b/src/compiled/examples/fldist-sample.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/fold.ts b/src/compiled/examples/fold.ts
index 71f29ef..15b7d40 100644
--- a/src/compiled/examples/fold.ts
+++ b/src/compiled/examples/fold.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/func.ts b/src/compiled/examples/func.ts
index 3e3453a..f5186fb 100644
--- a/src/compiled/examples/func.ts
+++ b/src/compiled/examples/func.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/helloWorld.ts b/src/compiled/examples/helloWorld.ts
index 1d10398..317465e 100644
--- a/src/compiled/examples/helloWorld.ts
+++ b/src/compiled/examples/helloWorld.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/if.ts b/src/compiled/examples/if.ts
index 00b719c..285a39d 100644
--- a/src/compiled/examples/if.ts
+++ b/src/compiled/examples/if.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/on.ts b/src/compiled/examples/on.ts
index 9407a16..0cecfde 100644
--- a/src/compiled/examples/on.ts
+++ b/src/compiled/examples/on.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/par.ts b/src/compiled/examples/par.ts
index 66513f2..820d622 100644
--- a/src/compiled/examples/par.ts
+++ b/src/compiled/examples/par.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/println.ts b/src/compiled/examples/println.ts
index 6d24ded..94f6572 100644
--- a/src/compiled/examples/println.ts
+++ b/src/compiled/examples/println.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/stream.ts b/src/compiled/examples/stream.ts
index 4c5f08c..ed8f6ad 100644
--- a/src/compiled/examples/stream.ts
+++ b/src/compiled/examples/stream.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/compiled/examples/topology.ts b/src/compiled/examples/topology.ts
index 96bb720..c691c25 100644
--- a/src/compiled/examples/topology.ts
+++ b/src/compiled/examples/topology.ts
@@ -3,7 +3,7 @@
  * This file is auto-generated. Do not edit manually: changes may be erased.
  * Generated by Aqua compiler: https://github.com/fluencelabs/aqua/. 
  * If you find any bugs, please write an issue on GitHub: https://github.com/fluencelabs/aqua/issues
- * Aqua version: 0.1.3-SNAPSHOT
+ * Aqua version: 0.1.4-SNAPSHOT
  *
  */
 import { FluenceClient, PeerIdB58 } from '@fluencelabs/fluence';
diff --git a/src/examples/useOptionalCall.ts b/src/examples/useOptionalCall.ts
new file mode 100644
index 0000000..02e8b92
--- /dev/null
+++ b/src/examples/useOptionalCall.ts
@@ -0,0 +1,21 @@
+import {FluenceClient, registerServiceFunction} from "@fluencelabs/fluence";
+import {getTwoResults} from "../compiled/examples/foldJoin";
+import {useOptional} from "../compiled/examples/option";
+
+export async function useOptionalCall(client: FluenceClient): Promise<string> {
+    registerServiceFunction(client, "test2", "getStr", (args: any[], _) => {
+        console.log("getStr:")
+        console.log(args)
+        return args[0]
+    })
+
+    registerServiceFunction(client, "test2", "getStr2", (args: any[], _) => {
+        console.log("getStr2:")
+        console.log(args)
+        return args[0]
+    })
+
+    let cbEm = (str: string) => console.log(str)
+    let cb = (str: string, arg: any) => console.log(str, arg)
+    return await useOptional(client, "hello", cbEm, cb, cb)
+}
diff --git a/src/run-examples.ts b/src/run-examples.ts
index c1507b2..c8870b0 100644
--- a/src/run-examples.ts
+++ b/src/run-examples.ts
@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 
-import {createClient, registerServiceFunction} from "@fluencelabs/fluence";
+import {createClient, registerServiceFunction, setLogLevel} from "@fluencelabs/fluence";
 import {testNet} from "@fluencelabs/fluence-network-environment";
 import {callArrowCall} from "./examples/callArrowCall";
 import {dataAliasCall} from "./examples/dataAliasCall";
@@ -15,13 +15,16 @@ import {constantsCall} from "./examples/constantsCall";
 import {streamCall} from "./examples/streamCall";
 import {topologyCall} from "./examples/topologyCall";
 import {foldJoinCall} from "./examples/foldJoinCall";
+import {useOptionalCall} from "./examples/useOptionalCall";
 let deepEqual = require('deep-equal')
 
 function checkCall(name: string, expected: any, actual: any, callBackOnError: () => void) {
   if (!deepEqual(actual, expected)) {
     console.error(`${name} call has the wrong result`)
-    console.error("expected: " + expected)
-    console.error("actual: " + actual)
+    console.error("expected: ")
+    console.dir(expected)
+    console.error("actual: ")
+    console.dir(actual)
     callBackOnError()
   }
 }
@@ -35,6 +38,7 @@ function checkCallBy(name: string, actual: any, by: (res: any) => boolean, callB
 }
 
 const main = async () => {
+  // setLogLevel("trace")
   const client = await createClient(testNet[0]);
   const client2 = await createClient(testNet[1]);
 
@@ -89,6 +93,9 @@ const main = async () => {
   // foldJoin.aqua
   let foldJoinResult = await foldJoinCall(client)
 
+  // option.aqua
+  let optionResult = await useOptionalCall(client)
+
   await client.disconnect();
 
   let success = true;
@@ -120,6 +127,8 @@ const main = async () => {
 
   checkCallBy("foldJoinCall", foldJoinResult, (res) => res.length == 3, cb)
 
+  checkCall("useOptional", optionResult, "hello", cb)
+
   if (success) {
     process.exit(0)
   } else {