anchor.diff:  (def (function e) effective-keyword-name-of (k)
     (or (keyword-name-of k)
         (intern (symbol-name (name-of k)) :keyword)))
  -
  -(defun walk-keyword-argument (form parent env)
  -  (destructuring-bind (name &optional (default-value nil default-value-supplied?) supplied-p-parameter-name)
  -      (ensure-list form)
  -    (let ((name (if (consp name)
  -                    (second name)
  -                    name))
  -          (keyword (if (consp name)
  -                       (first name)
  -                       nil)))
  -      (with-form-object (arg 'keyword-function-argument-form parent
  -                             :name name
  -                             :keyword-name keyword
  -                             :supplied-p-parameter-name supplied-p-parameter-name)
  -        (when default-value-supplied?
  -          (setf (default-value-of arg) (walk-form default-value :parent arg :environment env)))))))
   
   (def unwalker keyword-function-argument-form (keyword-name name default-value supplied-p-parameter-name)
     (bind ((default-value (awhen (default-value-of -form-)
  
positive.code: 
  (def form-class optional-function-argument-form (function-argument-form-with-supplied-p-parameter)
    ())
  
  (defun walk-optional-argument (form parent env)
    ;; TODO report bind bug: (bind (((name &optional (default-value nil default-value-supplied?) supplied-p-parameter) (ensure-list form))) )
    (destructuring-bind (name &optional (default-value nil default-value-supplied?) supplied-p-parameter-name)
        (ensure-list form)
      (with-form-object (arg 'optional-function-argument-form parent
                             :name name
                             :supplied-p-parameter-name supplied-p-parameter-name)
        (when default-value-supplied?
          (setf (default-value-of arg) (walk-form default-value :parent arg :environment env))))))
  
  (def unwalker optional-function-argument-form (name supplied-p-parameter-name)
    (bind ((default-value (awhen (default-value-of -form-)
  
negative.code: 
  (def form-class specialized-function-argument-form (required-function-argument-form)
    ((specializer)))
  
  (def unwalker specialized-function-argument-form (name specializer)
    (if (eq specializer t)
  