Write the following in Scheme function in Racket language:

unfirl - takes a list of atoms and returns the unfirled version of the list. Unfirling a list means extracting the centermost element and putting it at the front of the list, then repeating the process until the entire list is unfirled. For example, (unfirl '(8 5 9 6 4)) should return the list (9 5 6 8 4). If the list has an even number of elements, the centermost value would be last element of the first half of the list. For example, (unfirl '(7 8 3 4)) would return (8 3 7 4). Note: you may have to define some additional functions to solve this problem.