   (setq-local indent-line-function #'fstar-indent)
   (electric-indent-local-mode -1))
 
-;;; Interaction with the server
+;;; Interaction with the server (interactive mode)
 
 (defconst fstar-subp--success "ok")
 (defconst fstar-subp--failure "nok")
 (defconst fstar-subp--done "\n#done-")
 
+(defconst fstar-subp--cancel "#pop\n")
 (defconst fstar-subp--header "#push\n")
 (defconst fstar-subp--footer "\n#end #done-ok #done-nok\n")
 


(defun fstar-subp-remove-unprocessed ()
  "Remove pending and busy overlays."
  (cl-loop for overlay in (fstar-subp-overlays)
           unless (fstar-subp-status-eq overlay 'processed)
           do (delete-overlay overlay)))


      (fstar-subp-kill)
      (error "Invalid state: Received output, but no region was busy"))
    (setq fstar-subp--busy-now nil)
    (fstar-subp-clear-issues)
    (pcase status
      (`t   (fstar-subp-handle-success response overlay))
      (`nil (fstar-subp-handle-failure response overlay))
