anchor.diff:             (cxml:with-element "x"
                (cxml:attribute "xmlns" xmlns)
                (cxml:attribute "type"  x-type)
  -             (mapcar #'(lambda (i) (cxml:with-element "instruction"
  +             (mapcar #'(lambda (i) (cxml:with-element "instructions"
                                        (cxml:text i)))
                        instructions)
                (mapcar #'stanza-to-xml fields)
  
positive.code:            stanza))
  
         (stanza-to-xml ((stanza))
           (with-slots (desc required values options label var element-type)
               (cxml:with-element "field"
                 (unless (null label)
                   (cxml:attribute "label" label))
                 (unless (null var)
                   (cxml:attribute "var" var))
                 (unless (null element-type)
                   (cxml:attribute "type" element-type))
                 (unless (null desc)
                   (cxml:with-element "desc"
                     (cxml:text desc)))
                 (unless (null required)
                   (cxml:with-element "required"))
                 (mapcar #'(lambda (v) (cxml:with-element "value" (cxml:text v))) field-values)
                 (mapcar #'(lambda (o) (cxml:with-element "options" (cxml:text o))) options)))))))
  
     (field-option-element (meta-element)
       (option-values label)
  
negative.code:                         :description "XEP 0004, Data Forms")
  
    ;;
    ;; Current XEP contains no 'stanzas', instead it contains regular xml-elements
    ;; with the same meaning as the `stream-element` "stanza" has.
    ;;
    ;; All elements presented here actually are building blocks for other "stanzas",
    ;; it means that they will never be a top-level element (child of "<stream:stream>").
    ;;
    ;; Also, in fact this code serializes/deserializes from/to XML and does nothing else
    ;; according to the given XML Schema -- http://xmpp.org/extensions/xep-0004.html#schema,
    ;; and I believe that the rest of XMPP also shouldn't contain additional logic, so my
    ;; idea is to generate such code using "XSD to S-exp" generator.
    ;;
    
    ((x-element (meta-element)
  