diff --git a/src/helper.ts b/src/helper.ts
new file mode 100644
index 0000000..6e1aca3
--- /dev/null
+++ b/src/helper.ts
@@ -0,0 +1,33 @@
+import { Stock } from "./stock";
+const request = require('request');
+
+const BASE_API_URL = 'https://api.vietstock.vn/ta/history';
+const buildApiUrl = (stockCode: string): string => {
+    const to = Math.floor(Date.now() / 1000);
+    const from = to - 864000; // 10 days
+    return `${BASE_API_URL}?symbol=${stockCode}&resolution=D&from=${from}&to=${to}`;
+}
+
+const fetchStock = async (stockCode: string): Promise<Stock> => {
+    const apiCall = () => {
+        return new Promise((resolve, reject) => {
+            const options = {
+                url: Helper.buildApiUrl(stockCode),
+                method: 'GET',
+                json: true
+            };
+            request(options, (err: any, _res: any, body: any) => {
+                if (err) reject(err);
+                resolve(body);
+            });
+        })
+    }
+    return apiCall().then((body: any) => {
+        return new Stock(stockCode, JSON.parse(body));
+    })
+}
+
+export const Helper = {
+    buildApiUrl: buildApiUrl,
+    fetchStock: fetchStock
+}
diff --git a/src/index.ts b/src/index.ts
index fb70055..f8eb9fc 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -17,6 +17,11 @@ program
                 }
                 Stock.gets(stocks);
             case "stream":
+                if (stocks.length == 0) {
+                    console.log("You must include stock code!! For example: ");
+                    console.log("`stocknode stream VCB`");
+                    return;
+                }
                 Stock.stream(stocks[0]);
                 break;
             default:
diff --git a/src/stock_api.ts b/src/stock_api.ts
index f654db2..58d3a9b 100644
--- a/src/stock_api.ts
+++ b/src/stock_api.ts
@@ -1,22 +1,12 @@
-import { Stock } from './stock';
-const request = require('request');
-
-const BASE_API_URL = 'https://api.vietstock.vn/ta/history';
+import { Helper } from './helper';
 
 const gets = (stockCodes: string[]) => {
     console.log(`Stock\tPrice\t\tVolume\t\tOpenPrice\tHighestPrice\tLowestPrice\tTime`);
     try {
-        return Promise.all(stockCodes.map(code => {
-            const options = {
-                url: buildApiUrl(code),
-                method: 'GET',
-                json: true
-            }
-            return request(options, (_err: any, _res: any, body: any) => {
-                const stockPrice = new Stock(code, JSON.parse(body));
-                stockPrice.printf();
-                return true;
-            });
+        return Promise.all(stockCodes.map(async (code) => {
+            const stock = await Helper.fetchStock(code);
+            stock.printf();
+            return true;
         }));
     } catch (err) {
         throw err;
@@ -27,12 +17,6 @@ const stream = (stockCode: string) => {
     return;
 }
 
-const buildApiUrl = (stock: string): string => {
-    const to = Math.floor(Date.now() / 1000);
-    const from = to - 864000; // 10 days
-    return `${BASE_API_URL}?symbol=${stock}&resolution=D&from=${from}&to=${to}`;
-}
-
 export {
     gets,
     stream