Add data handling for transactions and stocks

frontend/src/app/Helpers/helper.service.ts

@@ -1,10 +1,8 @@
 import { Injectable } from '@angular/core';
-import { Stock } from '../Models/stock.model';
 
 @Injectable({
-  providedIn: 'root'
+  providedIn: 'root',
 })
 export class HelperService {
-
-  constructor() { }
+  constructor() {}
 }