def transfer(bank, login, user, user, amount): ''' In this function, you will try to make a transfer between two user accounts. bank is a dictionary where the key is the username and the value is the user's account balance. log_in is a dictionary where the key is the username and the value is the user's log-in status. amount is the amount to be transferred between user accounts (userA and userA). amount is always positive. What you will do: - Deduct the given amount from userA and add it to userB, which makes a transfer. - You should consider some following cases: - userA must be in the bank and his/her log-in status in log_in must be True. - userB must be in log_in, regardless of log-in status. userB can be absent in the bank. - No user can have a negative amount in their account. He/she must have a positive or zero balance. Return True if a transfer is made. For example: