anchor.diff:  
   (define-test test-limits-of-case
       "case is not suitable for all kinds of values, because
  -     it uses the function eql for comparisons. We will explore 
  +     it uses the function eql for comparisons. We will explore
        the implications of this in the equality-distinctions lesson"
     (let* ((name "John")
            (lastname (case name ("John" "Doe")
                                 ("Max" "Mustermann")
                                 (t "Anonymous"))))
  -  (assert-equal ____ lastname)))
  +  (assert-equal "Anonymous" lastname)))
   
   (define-test test-cond
       "cond is the general purpose form for checking multiple
  
positive.code:      lexical form.  After which, the previous value, if it exists, is visible again."
    (setf a 10)
    (setf b 20)
    (assert-equal a ___)
    (assert-equal b ___)
    (let ((a 1111)
          (b 2222))
      (assert-equal a ___)
      (assert-equal b ___))
    (assert-equal a ___)
    (assert-equal b ___))
  
  
  (define-test test-let-default-value
      "let vars have a default value"
      (let ((x))
        (assert-equal ___ x)))
  
  (define-test test-let-bindings-are-parallel
      "When defining the bindings in the let form, later bindings may not depend
  
negative.code:                 (5 :five)
                  ;; t specifies default behavior
                  (t :unknown)))
    (assert-equal :four b)
    "case can also check if a list of values contains
     the input"
    (setf c
          (case a (5 :five)
                  ((3 4) :three-or-four)))
    (assert-equal :three-or-four c))
  
  (defun cartoon-dads (input)
      "you should be able to complete this case statement"
    (case input (:this-one-doesnt-happen :fancy-cat)
                (:bart :homer)
                (:stewie :peter)
                (:stan :randy)
                (t :unknown)))
  
  (define-test test-your-own-case-statement
  