anchor.diff:    (setf a 100)
     (let ((a 5)
           (b (* 10 a)))
  -    (assert-equal b ___)))
  +    (assert-equal b 1000)))
   
   (define-test test-let*-bindings-are-series
       "let* is like let, but successive bindings may use values of previous ones"
  
positive.code:     "setf is used to assign values to symbols.  These symbols may 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:      lexical form.  After which, the previous value, if it exists, is visible again."
    (setf a 10)
    (setf b 20)
    (assert-equal a 10)
    (assert-equal b 20)
    (let ((a 1111)
          (b 2222))
      (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 nil x)))
  
  (define-test test-let-bindings-are-parallel
      "When defining the bindings in the let form, later bindings may not depend
  