anchor.diff:       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 ___)
  +  (assert-equal a 10)
  +  (assert-equal b 20)
     (let ((a 1111)
           (b 2222))
  -    (assert-equal a ___)
  -    (assert-equal b ___))
  -  (assert-equal a ___)
  -  (assert-equal b ___))
  +    (assert-equal a 1111)
  +    (assert-equal b 2222))
  +  (assert-equal a 10)
  +  (assert-equal b 20))
   
   
   (define-test test-let-default-value
       "let vars have a default value"
       (let ((x))
  -      (assert-equal ___ x)))
  +      (assert-equal nil x)))
   
   (define-test test-let-bindings-are-parallel
       "When defining the bindings in the let form, later bindings may not depend
  
positive.code:     "setf is used to assign values to symbols.  These symbols my refer to
       variables with lexical or dynamic scope."
    (setf my-name "David")
    (assert-equal my-name ____)
    " In SBCL, if the symbol isn't defined as a variable, via a top-level defvar
    or let statement, the setf call may result in a warning."
    (setf my-clones-name my-name)
    (assert-equal "David" ____)
    (setf a 5)
    (setf b 10)
    (setf c ___)
    (assert-equal 50 c))
  
  
  
negative.code:   (setf a 100)
    (setf b 23)
    (setf c 456)
    (let ((a 100)
          (b 200)
          (c "Jellyfish"))
      (assert-equal a 100)
      (assert-equal b 200)
      (assert-equal c "Jellyfish"))
    (let* ((a 121) (b 200) (c 14841/121))
      (assert-equal a 121)
      (assert-equal b 200)
      (assert-equal c (+ a (/ b a)))))
  