04. (Part A, 5 points) Suppose you are given a definition of an exception class, which raises an error message when an username cannot be found in the list of username. See the definition below: usernames ('ABC', 'DEF') #list of accepted usernames class UsernameNotFound(Exception): def-init-(self, username): #dummy initialization of username self.username username def_ str_(self ): return self.username+"not found!" Suppose user enters an invalid usernameXYZ' "XYZ' is not present in the list of accepted usernames. Define and handle the appropriate exception for this class using try-except. Your answer here: (Part B, 5 point) Suppose you are designing a FIFO (First in first out) queue for a message passing system and you need to receive(put) and deliver (get) stream of messages. Each of the message is separated with a comma() and has a timestamp with it in the format of Month- Day. Message and timestamp are separated by a # character. "Hi there#Jan-20", "Hello again#Jan-10", "See u tomorrow#Mar-29", "Got ticketesiFeb4" Write down the order the messages will be received (note the timestamp). 1. 2. 3. 4. Write down the order of the messages they will be delivered. 1. 2. 3 4