anchor.diff:  ; a form generates the message
   (keybind-common l snormal snormal ((focus right)) (coerce (coerce "focus right" 'list) 'string))
   (keybind-common l snormal snormal ((focus right)) "")
  +(keybind-common ^z raw screen ())
   
   (defun normalize-cmd-format (cmd)
     (cond ((null cmd) '())
  
positive.code:     with quote."
    (concat-str "'" str "'"))
  
  (defun secho-arg (str)
    " An argument for echo command of screeen must be wrapped
      with double quote."
    (concat-str "\"" str "\""))
  
  (defun state-leave-desc (state)
  
negative.code: (keybind ^c raw screen ((focus up)) ())
  (keybind ^p window-select window-select
           ((prev))
           ((echo (sstringarg "[window-select] (prev)"))))
  
  (let ((x "focus down")
        (y "-v"))
  