anchor.diff:  (define-test "LAST return NIL for empty list"
     ((last nil))
     nil)
  +
  +
  +; + - * / MOD
  +; LOGXOR
  +; MAKE-SYMBOL ATOM SYMBOL-VALUE %TYPE-ID
  +; SYMBOL-FUNCTION SYMBOL-PACKAGE
  +; BOUNDP FBOUNDP
  +; MACROP STRINGP
  +; = < >
  +; BIT-OR BIT-AND
  +; << >>
  
positive.code:   ((car nil))
    nil)
  
  (define-test "ATOM recognizes atoms"
    ((atom nil))
    t)
  
negative.code: ;  ((functionp #'block))
  ;  nil)
  
  (define-test "STRINGP recognizes strings"
    ((stringp "some string"))
    t)
  
  (define-test "STRINGP fails on numbers"
    ((stringp 1))
    nil)
  
  (define-test "STRINGP fails on symbols"
    ((stringp 'a))
    nil)
  
  (define-test "CODE-CHAR converts number to char"
  