If anyone can help with this Python assignment, I thank you very much!

Create a program that will simulate a login to a system. The program needs to meet the following requirements:

1. The program needs to execute forever.

2. The program needs to ask the user if he/she is a new or existing user and should accept the following enteries only: Yes, yes, no, No. Other enteries will be considered as bugs in the program.

3. If the user is a new user, the program needs to walk the user through the following signup process:

a- Ask the user to enter first name.

b- Ask the user to enter last name.

c- Create a username based on the user's first and last name. You can use the slicing technique to create the username.

d- Ex: username = Firstname[0] + Lastname[0]

e- Print the username for the user.

f- Append the username to predefined list.

4. If it's an existing user, the program needs to prompt the user to enter his/her username to check if the user exists. If he/she is an existing user, the program needs to print a message to inform the user that access is granted.

5. If the user is non-existing user, the program needs to ask the user to re-enter username.

Again any help is appreciated! I am having most of my trouble with steps: 2,4,&5. Thank you.