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Problem: 5.1
Authors: Hannibal F. and Cannibal G.
Date:    January 20, 2000

A list of indices is either
 * empty
 * (cons i loi)
    where i is an index and loi is a list of indices.
 [self-reference: from loi to list of indices]

An index is an integer between 0 and 9.
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;; remove : index list-of-indices -> list-of-indices
;; Examples: 
;; (remove 0 (list 0 1 2 0 3)) = (list 1 2 3)
(define (remove an-i a-loi)
  (cond
    [(empty? a-loi) empty]
    [else (cond
	    [(eq? (first a-loi) an-i)
	     (remove an-i (rest a-loi))]
	    [else (cons (first a-loi)
		    (remove an-i (rest a-loi)))])]))

#| Tests: the simplest tests to check return #t: 
(equal? (remove 0 (list 0 1 2 0 3)) (list 1 2 3))
(equal? (remove 2 (list 0 1 2 0 3)) (list 0 1 0 3))	
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