;;
;; FILE:     homework04.rkt
;; AUTHOR:   [ YOUR NAME ]
;; DATE:     [ YOUR DATE ]
;; COMMENT:  This module defines the five functions specified in
;;           Homework 4 as an importable module.
;;
;; MODIFIED: 
;; CHANGE:   
;;

#lang racket
(require rackunit)      ; enables you to use rackunit tests
(provide every?         ; exports your functions to client code
         reject         ;      You must define a function with
         interleave     ;      each name, even if the function
         cons-at-end    ;      only returns a default value!
         positions-of)

;; --------------------------------------------------------------------------
;; Problem 1                                           (structural recursion)
;; --------------------------------------------------------------------------

'YOUR-CODE-HERE     ; delete this line when you write code

'YOUR-TESTS-HERE    ; delete this one, too :-)

;; --------------------------------------------------------------------------
;; Problem 2                                           (structural recursion)
;; --------------------------------------------------------------------------

'YOUR-CODE-HERE

'YOUR-TESTS-HERE

;; --------------------------------------------------------------------------
;; Problem 3                                           (structural recursion)
;; --------------------------------------------------------------------------

'YOUR-CODE-HERE

'YOUR-TESTS-HERE

;; --------------------------------------------------------------------------
;; Problem 4                                           (structural recursion)
;; --------------------------------------------------------------------------

'YOUR-CODE-HERE

'YOUR-TESTS-HERE

;; --------------------------------------------------------------------------
;; Problem 5                   (structural recursion and interface procedure)
;; --------------------------------------------------------------------------

'YOUR-CODE-HERE

'YOUR-TESTS-HERE

;; --------------------------------------------------------------------------