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; == Homework 6, Problem 3 ==
; TODO #1: design the function item-counts that accepts a list of
; elements, a transformation function, and an equality function,
; and counts the distinct transformation results.
; The transformation function takes an element from the list and
; produces a result. The equality function takes two results of
; the transformation function and determines if they are the same.
; As a motivating example, consider counting words (supplied as
; strings): the transformation might convert each string to lower-case,
; the equality would then compare two strings to see if they are
; equal; and the resulting counts would be a list of pairings of
; distinct-lower-case words and how many times they appeared in the
; original list. SO… in case of Peter Piper
; (https://en.wikipedia.org/wiki/Peter_Piper), supplied as a list of
; strings without punctuation, you would learn that “peter” occurs 4
; times (as do “piper”, “picked”, “pickled”, and “peppers”); “a”
; appears 3 times, and “if” appears 1 time (as does “where”, “is”,
; and “the”).
; The function result should be a list, where each element is a
; pairing between a distinct transformation result and a count
; of how many times that result has occurred in the original list.
; You should design this data as a first step.
; You’ll then design item-counts to consider each element of the
; supplied list in order. For each element, transform it and then
; add the result to the count. Adding is a bit tricky: first you
; check if that result has already been seen (and, if so, +1 to the
; associated counter); otherwise, add a new count pair of 1 to the end.