anchor.diff:                   (if (equal (layer-type layer) :output) 0 1))))
       (setf (neuron-count layer) size)
       (setf (neuron-array layer)
  -          (make-array size :element-type 't-neuron :fill-pointer 0))
  +          (make-array size :fill-pointer 0))
       (loop for a from 0 below size do
            (vector-push
             (make-instance 't-neuron
                            :layer (layer-index layer)
                            :layer-type (layer-type layer)
  +                         :index-in-layer a
                            :biased (and (not (equal (layer-type layer) :output))
                                         (= a (1- size)))
                            :net (net layer)
  
positive.code:        (set-layer-transfer-function net (layer-index layer) transfer-tag)))
  
  (defmethod transfer ((neuron t-neuron))
    (setf (output neuron)
          (funcall (transfer-function neuron) (input neuron)))
    neuron)
  
negative.code:    (layer-type :accessor layer-type :initarg :layer-type :initform nil)
     (biased :reader biased :initarg :biased :initform nil :type boolean)
     (id :accessor id :type integer)
     (index-in-layer :accessor index-in-layer :initarg :index-in-layer :type integer)
     (input :accessor input :initform 0.0 :type real)
     (transfer-tag :accessor transfer-tag :initarg :transfer-tag :initform :sigmoid)
     (transfer-function :accessor transfer-function :initform nil)
  