anchor.diff:                      (not (cached-p chunk)))))
         ;; Zero activations or copy cached activations coming from
         ;; conditioning chunks.
  -      (dolist (chunk chunks)
  -        (unless (conditioning-chunk-p chunk)
  -          (if (cached-p chunk)
  -              (progn
  -                ;;(format *trace-output* "Copy act: ~A~%" chunk)
  -                (copy-chunk-nodes chunk (static-activations chunk)
  -                                  (nodes chunk)))
  -              (zero-chunk chunk))))
  +      (unless addp
  +        (dolist (chunk chunks)
  +          (unless (conditioning-chunk-p chunk)
  +            (if (cached-p chunk)
  +                (progn
  +                  ;;(format *trace-output* "Copy act: ~A~%" chunk)
  +                  (copy-chunk-nodes chunk (static-activations chunk)
  +                                    (nodes chunk)))
  +                (zero-chunk chunk)))))
         ;; Calculate the activations coming from conditioning chunks if
         ;; they are to be cached.
         (flet ((foo (to-chunk from-chunk cloud)
  
positive.code:                                              *static-activation-contexts*)))
       ,@body))
  
  (defun hijack-means-to-activation (chunks clouds bm)
    "Set NODES of CHUNKS to the activations calculated from CLOUDS. Skip
  chunks that don't need activations."
    (destructuring-bind (static-activations-context static-chunks)
  
negative.code:           (unless (= #.(flt 0) damping-factor)
              (sum-nodes-and-old-nodes chunks
                                       (flt (- 1 damping-factor))
                                       (flt damping-factor)))))
    (map nil #'nodes->means chunks))
  
  (defun settle-visible-mean-field
      (bm &key (supervisor (default-mean-field-supervisor bm)))
  