#lang scheme

;; invert
;;
;; takes a list of 2-lists and returns a list with each 
;; 2-list reversed
(define
  (invert list)
  list
)

;; vector-index
;;
;; returns the zero-based index of the first occurrence of
;; a parameter in a vector, or -1 if there is no occurrence
(define
  (vector-index needle haystack)
  haystack
)

;; count-occurrences
;; 
;; returns the number of occurrences of a parameter in a list
(define
  (count-occurrences needle haystack)
  haystack
)

;; compose23
;;
;; 
(define
  (compose23 a b c)
  (a (b c))
)