anchor.diff:  (defun ids-path-to-pill (x y map-tree width treedepth)
       (ids 1             ;; could also start with bigger search for speed
                          ;; (at the expense of accuracy, of course)
  -         (cons (cons (cons x y) 0) 0) ;; search node in list
  +         (cons
  +            (cons 0 (cons (cons x y) 0))
  +            0) ;; search node in list
            0
            map-tree width treedepth))
   
  
positive.code:                         0)))) )
  
  (defun build-search-node ()
    (cons (cons 1 1) 0))
  
  (defun build-demo-world ()
    (cons (build-map)
  
negative.code: 
  (defun search-node-is-dot (searchnode map-tree width treedepth)
    (member
      (map-tree-lookup (car (car (cdr searchnode)))
                       (cdr (car (cdr searchnode)))
                       map-tree
                       width
                       treedepth)
  