anchor.diff:    ;; `return-immediate' and `cancel-input', e.g. `hide', the normalization of
     ;; the input-buffer, etc.
     (hide *interface*)
  -  (with-slots (callback-function cleanup-function
  +  (with-slots (callback cleanup-function
                  empty-complete-immediate completions completion-cursor)
         minibuffer
       (if completions
  
positive.code:    (callback-buffer :initarg :callback-buffer :accessor callback-buffer :initform (when *interface* (active-buffer *interface*))
                      :documentation "The active buffer when the minibuffer was
  brought up.  This can be useful to know which was the original buffer in the
  `callback-function' in case the buffer was changed.")
     (setup-function :initarg :setup-function :accessor setup-function :initform #'setup-default
                     :documentation "Function of no argument that fills the
  `content' on when the minibuffer is created.  Called only once.")
  
negative.code:                                completion)))
            (if completion
                ;; if we're able to find a completion
                (funcall callback completion)
                ;; if we can't find a completion
                (when empty-complete-immediate
                  ;; TODO: Test if we ever reach here since we have the "raw input" as candiate now.
                  ;; if we accept immediate output in place of completion
                  (return-immediate minibuffer))))
          ;; if there's no completion function
  