anchor.diff:  
     (setf (gethash 8 table-of-cube-roots) 2)
     (setf (gethash -3 table-of-cube-roots) -27)
  -  (assert-equal ___ (gethash -3 table-of-cube-roots))
  -  (assert-equal ___ (hash-table-count table-of-cube-roots))
  +  (assert-equal -27 (gethash -3 table-of-cube-roots))
  +  (assert-equal 3 (hash-table-count table-of-cube-roots))
   
     "accessing unset keys returns nil"
  -  (assert-equal ___ (gethash 125 table-of-cube-roots))))
  +  (assert-equal nil (gethash 125 table-of-cube-roots))))
   
   
   (define-test test-hash-key-equality
  
positive.code:     "make hash table with make-hash-table"
    (let ((my-hash-table))
      (setf my-hash-table (make-hash-table))
      (true-or-false? ___ (typep my-hash-table 'hash-table))
      (true-or-false? ___  (hash-table-p my-hash-table))
      (true-or-false? ___  (hash-table-p (make-array '(3 3 3))))
      (assert-equal ___ (hash-table-count my-hash-table))))
  
  
  (define-test test-hash-table-access
  
negative.code:     (setf (gethash "one" hash-table-default) "uno")
  
      "count how many unique key-value pairs in each"
      (assert-equal 2 (hash-table-count hash-table-eq))
      (assert-equal 1 (hash-table-count hash-table-equal))
      (assert-equal 2 (hash-table-count hash-table-default))))
  
  
  (define-test test-hash-table-equality
  