anchor.diff:                :initform (now))
      (last-iteration :accessor last-iteration
                      :initform 0)
  +   (current-stack :accessor current-stack
  +                  :initarg :starting-stack
  +                  :initform :main)
      (main-stack :accessor main-stack
                  :initform (make-string 0))
      (other-stack :accessor other-stack
  
positive.code:   "Check if the current other stack matches one of the presets yet.
  Return the associated value if match, nil otherwise."
    (cdr (assoc (other-stack *current-instance*)
                (assoc :other-stack-matches (program *current-instance*)))))
  
  ;;; Stack operations
  (defun append-to-main-stack (character)
    "Add a character to the main stack."
    (setf (main-stack *current-instance*)
          (concatenate 'string (main-stack *current-instance*)
                       (string character))))
  (defun append-to-other-stack (character)
    "Add a character to the other stack.
  
  After this, check if the current other stack matches an existing stack.
  If so, delete and append associated cahracter."
    (setf (other-stack *current-instance*)
          (concatenate 'string (other-stack *current-instance*)
                       (string character)))
    (let ((found-match (match-other-stack)))
      (when found-match
        (append-to-main-stack (cdr found-match)))))
  
  (defun modify-main-stack (character)
    "Change the last character of the main stack with something else."
    (setf (aref (main-stack *current-instance*)
                (1- (length *main-stack*)))
          character))
  
  (defun delete-main-stack ()
    "Delete the last character of the main stack."
    (setf (main-stack *current-instance*)
          (subseq (main-stack *current-instance*)
                  0 (- (length (main-stack *current-instance*)) 1))))
  (defun delete-other-stack ()
    "Delete the last character of the other stack."
    (setf (other-stack *current-instance*)
          (subseq (other-stack *current-instance*)
                  0 (- (length (other-stack *current-instance*)) 1))))
  
  (defun flush ()
    (uiop:run-program '("xclip" "-selection" "c")
                      :input (make-string-input-stream *main-stack*))
    (setf (main-stack *current-instance*) ""))
  
negative.code: (defvar *current-instance*)
  
  ;;; Load operations
  (defun load-profile (config-name)
    (setf *current-instance*
          (make-instance 'opengine-instance
                         :program (with-open-file (s config-name :external-format :utf-8)
  