anchor.diff:    (with-slots (status behavior heading environment parent) baby
       (let ((distance-to-parent (distance parent baby))
             (current-time (runtime environment)))
  -      (setf status (cond
  -                     ((> distance-to-parent 40) :separated)
  -                     ((> distance-to-parent 30) :too-far)
  -                     (t :content)))
  -      (setf behavior
  -            (case status
  -              (:content (behavior-new "meandering" .4 (+ 4 current-time)
  -                                      (make-meander-fn heading)))
  -              (:separated (behavior-new "separated" .7 (+ 1 current-time)
  -                                        (make-meander-fn heading)))
  -              (:too-far (behavior-new "returning" .6 (+ 1 current-time)
  -                                        (make-seek-fn baby parent))))))))
  +      (setf status (if (< distance-to-parent 30) :content :too-far))
  +      (setf behavior (if (eq status :content)
  +                         (behavior-new "meandering" .4 (+ 4 current-time)
  +                                      (make-meander-fn heading))
  +                         (behavior-new "returning" .6 (+ 1 current-time)
  +                                        (make-seek-fn baby parent)))))))
   
   (defmethod update ((sheep sheep))
     (with-slots (environment behavior expiration) sheep
  
positive.code:   (cairo-move-to cr (+ 5 x) (+ 5 y))
    (cairo-select-font-face cr "serif" 0 1)
    (cairo-set-font-size cr 10.0)
    (cairo-show-text cr text)
    (cairo-restore cr))
  
  
negative.code:         (cairo-fill cr))))
    (cairo-restore cr))
  
  (defmethod draw (cr (baby baby-sheep))
    (when *parent-lines-visible-p*
      (with-slots (x y parent) baby
        (let ((parent-x (x parent))
              (parent-y (y parent)))
          (cairo-set-line-width cr 2)
          (cairo-set-source-color cr purple)
          (cairo-move-to cr x y)
          (cairo-line-to cr parent-x parent-y)
          (cairo-stroke cr))))
    (call-next-method))
  
  (defmethod draw-heading-indicator (cr (mover mover))
    (cairo-set-source-color cr purple)
    (cairo-set-line-width cr 3.0)
  