anchor.diff:     (col :initarg :col :accessor col)
      (grid :initarg :grid :accessor grid)
      (halo :initform (make-instance 'halo) :accessor halo)
  -   (movement-actions :initform '() :accessor movement-actions)))
  +   (movement-actions :initform '() :accessor movement-actions)
  +   (claiming :initform nil :accessor claiming-p)))
   
   (defmethod initialize-instance :after ((player player) &rest initargs)
     (declare (ignore initargs))
  
positive.code: 
  (defun movement-possible-p (row col player)
    (and (valid-cell-p row col)
         (= cell-edge (cell-ref row col (grid player)))))
  
  
  
negative.code:                          collect (lambda ()
                                     (setf (pos player) target)
                                     (setf (row player) row)
                                     (setf (col player) col)
                                     (player-changed-cell player)))))))
      (when-let (move (find-if (lambda (move)
                                 (destructuring-bind (row col) move
                                   (movement-possible-p row col player)))
  