anchor.diff:  (defmethod erase-input ((minibuffer minibuffer))
     "Clean-up the minibuffer input."
     (setf (input-buffer minibuffer) "")
  -  (setf (input-buffer-cursor minibuffer) 0)
  +  (setf (input-cursor-position minibuffer) 0)
     (setf (content minibuffer) ""))
   
   ;; TODO: Move `erase-document' into the `show' function?
  
positive.code: (defun insert (characters &optional (minibuffer (current-minibuffer)))
    (setf (input-buffer minibuffer)
          (str:insert characters
                      (input-buffer-cursor minibuffer)
                      (input-buffer minibuffer)))
    (incf (input-buffer-cursor minibuffer) (length characters))
    (update-display minibuffer))
  
  (define-command self-insert ()
  
negative.code: 
  (define-command delete-forwards (&optional (minibuffer (current-minibuffer)))
    "Delete character after cursor."
    (with-accessors ((buffer input-buffer) (cursor input-cursor-position)) minibuffer
      (unless (= cursor (length buffer))
        (setf buffer
              (concatenate 'string
  