anchor.diff:    ())
   
   (defwalker-handler +atom-marker+ (form parent env)
  -  (declare (special *macroexpand*))
     (cond
       ((not (or (symbolp form) (consp form)))
        (make-instance 'constant-form :value form
  
positive.code:   (make-instance 'specialized-function-argument-form
                   :name (if (listp form)
                             (first form)
                             form) 
                   :specializer (if (listp form)
                                    (second form)
                                    'T)
  
negative.code:   (with-form-object (progn progn-form :parent parent :source form)
      (setf (body progn) (walk-implict-progn progn (cdr form) env))))
  
  ;;;; PROGV
  
  (defclass progv-form (form implicit-progn-mixin)
    ((vars-form :accessor vars-form :initarg :vars-form)
  