Set url function to private.

src/accounts/account.service.ts

@@ -12,13 +12,14 @@ export class AccountService {
     private http: HttpClient
   ) {}
 
-  url(id?: Number): string {
+  private url(id?: Number): string {
     if(id) {
       return `/api/account/${id}`;
     }
 
     return `/api/account`;
   }
+
   query(): Observable<Account[]> {
     return this.http.get<Account[]>(this.url());
   }

src/operations/operation.service.ts

@@ -23,7 +23,7 @@ export class OperationService {
     return date;
   }
 
-  url(id?: Number): string {
+  private url(id?: Number): string {
     if(id) {
       return `/api/operation/${id}`;
     }