anchor.diff:        progn block
         * / < >
         mod sqrt sin cos atan exp round floor
  -      last copy-list nthcdr nth member mapcar elt length make-string string
  +      last copy-list nthcdr nth member mapcar elt length make-string
         make-array aref code-char char-code integer
         make-symbol make-package
         symbol-name symbol-value symbol-function symbol-package
  
positive.code: ;;; 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
        ? functional
        builtin? macro?
        %%macroexpand %%macrocall %%%macro?
  
negative.code: 
  (defun eval (x) (%eval x))
  (defun macroexpand (x) (%%macroexpand x))
  (defun string (x) (%string x))
  
  (%load "environment/env-load-cl.lisp")
  