anchor.diff:  (defun macro? (x) (rassoc x *macros* :test #'eq))
   
   (defun =-aref (v x &rest indexes) v x (apply #'aref x indexes))
  +
  +(defun %make-hash-table (&key (test #'eql))
  +  (make-hash-table :test (? (eq test #'==)
  +                            #'eql
  +                            test)))
   
   (defun href (x i) (gethash i x))
   (defun =-href (x i) (setf (gethash i x) v))
  
positive.code:       %number? == %integer %+ %- %* %/ %< %>
        string== list-string
        =-aref
        href =-href
        ? functional
        builtin? macro?
        %%macroexpand %%macrocall %%%macro?
  
negative.code:       mod sqrt sin cos atan exp round floor
        last copy-list nthcdr nth mapcar elt length make-string
        make-array aref code-char char-code
        symbol-name make-package package-name
        logxor bit-and
        print
        defvar
        defun
        identity list copy-list
        &rest &body &optional &key
        labels))
  
  ;;; Functions we import from CL-USER, wrap and export to package TRE.
  (defconstant +renamed-imports+
  