anchor.diff:  		 :used-symbol-macros (dedup-used (used-symbol-macros env))
   		 :used-macros (dedup-used (used-macros env))
   		 :used-compiler-macros (dedup-used (used-compiler-macros env))))
  -
  -;;----------------------------------------------------------------------
  -
  -(defun filter-used-items (post-proc-obj)
  -  "This changes the code-object so that used-types only contains used
  -   'user' defined structs."
  -  (with-slots (code env) post-proc-obj
  -    (setf (used-types post-proc-obj)
  -	  (loop :for i :in (find-used-user-structs code env)
  -	     :collect (type-spec->type i :env env))))
  -  post-proc-obj)
   
   ;;----------------------------------------------------------------------
   
  
positive.code: 		#'compiler-macroexpand-pass)
  	#'compile-pass
  	#'make-post-process-obj
  	#'post-process-ast
  	#'filter-used-items
  	#'check-stemcells
  	#'gen-in-arg-strings
  	#'gen-out-var-strings
  	#'final-uniform-strings
  
negative.code: 
  ;;----------------------------------------------------------------------
  
  (defclass post-compile-process ()
    ((code :initarg :code :accessor code)
     (env :initarg :env :accessor env)
  