diff --git a/README.md b/README.md
index 6de142a..c39ffad 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,8 @@ In each sub directory is a set of examples
 
 ## Code generation
 
+`Currently, it's only compatiable with version 2.x.x`
+
 The code generation tool generates for a pattern an none generic version for spefici type
 
 ### Supported pattern
diff --git a/go.mod b/go.mod
index a2c0ce9..1af03db 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/donutloop/toolkit
 
 require github.com/fatih/astrewrite v0.0.0-20180730114054-bef4001d457f
+
+go 1.13
diff --git a/worker/doc_test.go b/worker/doc_test.go
index 2bcc741..39cbad7 100644
--- a/worker/doc_test.go
+++ b/worker/doc_test.go
@@ -7,15 +7,16 @@ import (
 )
 
 func ExampleWorker() {
-	workerHandler := func(parameter worker.GenericType) {
+	workerHandler := func(parameter interface{}) (interface{}, error) {
 		v := parameter.(string)
-		fmt.Println(v)
+		return v + " world", nil
 	}
 
-	queue := worker.New(2, workerHandler, 10)
+	request, response, _ := worker.New(2, workerHandler, 10)
 
-	queue <- "hello"
+	request <- "hello"
 	<-time.After(time.Millisecond * 250)
+	fmt.Println(<-response)
 
-	// Output: hello
+	// Output: hello world
 }
diff --git a/worker/worker.go b/worker/worker.go
index ff2038b..fedf3b0 100644
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -4,24 +4,34 @@ import (
 	"container/list"
 )
 
+type Request chan<- interface{}
+
+type Response <-chan interface{}
+
 type worker struct {
-	c    chan interface{}
-	done chan bool
-	jobs chan interface{}
-	fn   func(n GenericType)
-	buf  *list.List
+	request  chan interface{}
+	response chan interface{}
+	errs     chan error
+	done     chan bool
+	jobs     chan interface{}
+	fn       func(n interface{}) (interface{}, error)
+	buf      *list.List
 }
 
 // NewWorker starts n*Workers goroutines running func on incoming
 // parameters sent on the returned channel.
-func New(nWorkers uint, fn func(gt GenericType), buffer uint) chan<- interface{} {
-	retc := make(chan interface{}, buffer)
+func New(nWorkers uint, fn func(gt interface{}) (interface{}, error), buffer uint) (Request, Response, <-chan error) {
+	request := make(chan interface{}, buffer)
+	response := make(chan interface{}, buffer)
+	errs := make(chan error, buffer)
 	w := &worker{
-		c:    retc,
-		jobs: make(chan interface{}, buffer),
-		done: make(chan bool),
-		fn:   fn,
-		buf:  list.New(),
+		errs:     errs,
+		request:  request,
+		response: response,
+		jobs:     make(chan interface{}, buffer),
+		done:     make(chan bool),
+		fn:       fn,
+		buf:      list.New(),
 	}
 	go w.listener()
 	for i := uint(0); i < nWorkers; i++ {
@@ -32,11 +42,11 @@ func New(nWorkers uint, fn func(gt GenericType), buffer uint) chan<- interface{}
 			<-w.done
 		}
 	}()
-	return retc
+	return request, response, errs
 }
 
 func (w *worker) listener() {
-	inc := w.c
+	inc := w.request
 	for inc != nil || w.buf.Len() > 0 {
 		outc := w.jobs
 		var frontNode interface{}
@@ -67,7 +77,12 @@ func (w *worker) work() {
 				w.done <- true
 				return
 			}
-			w.fn(genericType)
+			v, err := w.fn(genericType)
+			if err != nil {
+				w.errs <- err
+				continue
+			}
+			w.response <- v
 		}
 	}
 }
diff --git a/worker/worker_test.go b/worker/worker_test.go
index c58ff34..3234b86 100644
--- a/worker/worker_test.go
+++ b/worker/worker_test.go
@@ -1,6 +1,7 @@
 package worker_test
 
 import (
+	"fmt"
 	"github.com/donutloop/toolkit/worker"
 	"sync/atomic"
 	"testing"
@@ -19,11 +20,10 @@ func TestWorker(t *testing.T) {
 	}
 
 	counter := int32(0)
-	workerHandler := func(parameter worker.GenericType) {
+	workerHandler := func(parameter interface{}) (interface{}, error) {
 		v, ok := parameter.(string)
 		if !ok {
-			t.Errorf("value is not a string got=%v", parameter)
-			return
+			return false, fmt.Errorf("value is not a string got=%v", parameter)
 		}
 
 		if !containes([]string{"hello", "golang", "world"}, v) {
@@ -32,13 +32,28 @@ func TestWorker(t *testing.T) {
 
 		t.Logf("value: %v", v)
 		atomic.AddInt32(&counter, 1)
+		return true, nil
 	}
 
-	queue := worker.New(3, workerHandler, 10)
+	request, response, errs := worker.New(3, workerHandler, 10)
 
-	queue <- "hello"
-	queue <- "golang"
-	queue <- "world"
+	request <- "hello"
+	request <- "golang"
+	request <- "world"
+
+	go func() {
+		for err := range errs {
+			t.Error(err)
+		}
+	}()
+
+	go func() {
+		for v := range response {
+			if !v.(bool) {
+				t.Error("bad type")
+			}
+		}
+	}()
 
 	<-time.After(500 * time.Millisecond)
 
diff --git a/worker/worker_type.go b/worker/worker_type.go
deleted file mode 100644
index dad1cdf..0000000
--- a/worker/worker_type.go
+++ /dev/null
@@ -1,4 +0,0 @@
-package worker
-
-// used for code generation replacing
-type GenericType interface{}