Recursion
The elements of tuple can be initialized so that tup[i] == i in a recursive fashion as follows:
A tuple of size 0 is already initialized
Otherwise:
set the last element of the tuple to n-1 (where n is the number of elements in the tuple)
initialize the portion of the tuple consisting of the first n-1 elements
Write a function named init that takes one argument, a tuple of the proper length, and returns an tuple initialized as described above.