anchor.diff:  
     (:export
   
  +   ;;;
  +   ;;; environment
  +   ;;;
      #:make-empty-lexenv
  +   #:lookup-in-lexenv
      #:macroexpand-all
   
      #:do-variables-in-lexenv
  
positive.code:    #:find-block-in-lexenv
     #:find-tag-in-lexenv
  
     #:form
     #:walk-form
     #:make-walk-environment
     #:*walk-handlers*
     #:*warn-undefined*
     #:undefined-reference
     #:undefined-variable-reference
     #:undefined-function-reference
     #:return-from-unknown-block
     #:defwalker-handler
     #:implicit-progn-mixin
     #:implicit-progn-with-declare-mixin
     #:binding-form-mixin
     #:declaration-form
     #:constant-form
     #:variable-reference
     #:local-variable-reference
     #:local-lexical-variable-reference
     #:free-variable-reference
     #:application-form
     #:local-application-form
     #:lexical-application-form
     #:free-application-form
     #:lambda-application-form
     #:function-form
     #:lambda-function-form
     #:function-object-form
     #:local-function-object-form
     #:free-function-object-form
     #:lexical-function-object-form
     #:function-argument-form
     #:required-function-argument-form
     #:specialized-function-argument-form
  
negative.code:    #:go-form
     #:the-form
     #:unwind-protect-form
  
     #:walk-lambda-list
     #:walk-implict-progn
     #:body
     #:cleanup-form
     #:code-of
     #:consequent
     #:declares
     #:default-value
  ;; #:else ; iterate
     #:enclosing-tagbody-of
     #:eval-when-times
     #:first-form
     #:func
     #:keyword-name
     #:name-of
     #:other-forms
     #:parent
     #:protected-form
     #:read-only-p
     #:result
     #:source
     #:specializer-of
     #:supplied-p-parameter
     #:tag
     #:target-block-of
     #:jump-target-of
     #:then
     ;;#:type-of
     #:value-of
     #:values-form
     #:variable-name-of
     #:vars-form
  
     ))
  