anchor.diff:  ;;; TAGBODY-AST (unlike hte TAGBODY special form) does not generate a
   ;;; value.
   
  +(defun tagp (item)
  +  ;; go tags are symbols or integers, per CLHS glossary.
  +  (or (symbolp item)
  +      (integerp item)))
  +
   (defmethod convert-special
       ((symbol (eql 'tagbody)) form env system)
     (db origin (tagbody . items) form
  
positive.code:     (let ((tag-asts
  	    (loop for item in (raw items)
  		  for raw-item = (raw item)
  		  ;; go tags are symbols or integers, per CLHS glossary.
  		  when (or (symbolp raw-item)
  			   (integerp raw-item))
  		    collect (cleavir-ast:make-tag-ast
  			     raw-item
  			     :origin (location item))))
  
negative.code: 	    do (setf new-env (cleavir-env:add-tag
  			      new-env (cleavir-ast:name ast) ast)))
        (let ((item-asts (loop for item in (raw items)
  			     collect (if (tagp (raw item))
  					 (pop tag-asts)
  					 (convert item new-env system)))))
  	(process-progn
  