anchor.diff:  during the learning or mean field is used instead. :HALF-HEARTED, the
   default value, samples the hiddens but uses the hidden means to
   calculate the effect of the positive and negative phases on the
  -gradient.")
  +gradient. The default should almost always be preferable to T, as it
  +is a less noisy estimate.")
      (n-gibbs
       :type (integer 1)
       :initform 1
       :initarg :n-gibbs
       :accessor n-gibbs
  -    :documentation "The number of steps of Gibbs sampling to perform."))
  +    :documentation "The number of steps of Gibbs sampling to perform.
  +This is how many full (HIDDEN -> VISIBLE -> HIDDEN) steps are taken
  +for CD learning, and how many times each chunk is sampled for PCD."))
     (:documentation "Paramaters for Markov Chain Monte Carlo based
   trainers for BMs."))
   
positive.code:                     :test #'equal)))
  
  (defun full-clouds-everywhere (visible-chunks hidden-chunks)
    "Return a list of cloud specifications suitable for instantiating an
  BM. Put a cloud between each pair of visible and hidden chunks unless
  they are both conditioning chunks. The names of the clouds are two
  element lists of the names of the visible and hidden chunks."
  
negative.code:     :initform (error "GROUP-SIZE must be specified.")
      :initarg :group-size
      :reader group-size))
    (:documentation "Means are normalized to SCALE within node groups of
  GROUP-SIZE."))
  
  (defmethod resize-chunk ((chunk normalized-group-chunk) size max-n-stripes)
  