anchor.diff:        (function? functionp)
         (string? stringp)
         (array? arrayp)
  -      (number? numberp)
         (character? characterp)
         (%+ +)
         (%- -)
  
positive.code:     '(%set-atom-fun cpr rplacp %load atan2 pow quit string-concat %load
        %eval %defun early-defun %defvar %defmacro %string %make-symbol
        %symbol-name %symbol-value %symbol-function %symbol-package
        ? functional
        builtin? macro?
        %%macroexpand %%macrocall %%%macro?
  
negative.code: (defun %symbol-package (x)
    (? (boundp x)
       (symbol-package x)))
  
  (defun %number? (x)
    (or (numberp x)
        (characterp x)))
  
  (defun %%macroexpand (x)
    (? *macroexpand-hook*
  