We define the required function as recursive_func().
The first line takes user input. The user input is stored in variable x.
The next line compares the user input to a string yes. The function executes the else block if the condition isn't met, that is a recursive call is executed.
IF condition returns the function. The string in variable X is compared to a string 'Yes'. the casefold() is a string function that ignores the upper/lower cases when comparing two strings. (This is important because a string 'yes' is not the same yes a string 'Yes' or 'YES'. Two equal strings means their cases and length should match).
