anchor.diff:  ;;; Things we have to implement ourselves.
   (defconstant +implementations+
       '(%set-atom-fun cpr rplacp %load atan2 pow quit string-concat %load
  -      %eval %defun early-defun %defvar %defmacro %string
  +      %eval %defun early-defun %defvar %defmacro %string %make-symbol
  +      %symbol-name %symbol-value %symbol-function %symbol-package
         ? functional
         builtin? macro?
         %%macroexpand %%macrocall %%%macro?
  
positive.code:      (format nil "~A" x)
       (string x)))
  
  (defun %%macroexpand (x)
    (? *macroexpand-hook*
        (funcall *macroexpand-hook* x)
  
negative.code:       mod sqrt sin cos atan exp round floor
        last copy-list nthcdr nth member mapcar elt length make-string
        make-array aref code-char char-code integer
        make-package
        logxor bit-and
        print
        defvar
  