- The user must be able to create a new transaction;
- The user must be able to obtain a summary of their account;
- The user must be able to list all occurred transactions;
- The user must be able to view a single transaction.
- The transaction can be of the credit type that adds to the total amount, or debit that will subtract;
- It must be possible to identify the user among the requests;
- The user can only view transactions which he created.