purpose we call greet_user()and that function prints an appropriate messageit either welcomes back an existing user or greets new user it does this by calling get_stored_username()which is responsible only for retrieving stored username if one exists finallygreet_user(calls get_new_username(if necessarywhich is responsible only for getting new username and storing it this compartmentalization of work is an essential part of writing clear code that will be easy to maintain and extend try it yourse lf - favorite numberwrite program that prompts for the user' favorite number use json dump(to store this number in file write separate program that reads in this value and prints the message" know your favorite numberit' - favorite number rememberedcombine the two programs from exercise - into one file if the number is already storedreport the favorite number to the user if notprompt for the user' favorite number and store it in file run the program twice to see that it works - verify userthe final listing for remember_me py assumes either that the user has already entered their username or that the program is running for the first time we should modify it in case the current user is not the person who last used the program before printing welcome back message in greet_user()ask the user if this is the correct username if it' notcall get_new_username(to get the correct username summary in this you learned how to work with files you learned to read an entire file at once and read through file' contents one line at time you learned to write to file and append text onto the end of file you read about exceptions and how to handle the exceptions you're likely to see in your programs finallyyou learned how to store python data structures so you can save information your users providepreventing them from having to start over each time they run program in you'll learn efficient ways to test your code this will help you trust that the code you develop is correctand it will help you identify bugs that are introduced as you continue to build on the programs you've written