anchor.diff:                                   gradient-source n-new-inputs)
     (assert (= 1 n-new-inputs))
     (assert (eq (momentum-type optimizer) :normal))
  +  (assert (not (use-segment-derivatives-p optimizer)) ()
  +          "PER-WEIGHT-BATCH-GD-OPTIMIZER does not support ~
  +          USE-SEGMENT-DERIVATIVES-P.")
     (let ((accumulator (accumulator optimizer))
           (n-weight-uses-in-batch (n-weight-uses-in-batch optimizer))
           (weight-deltas (weight-deltas optimizer))
  
positive.code:   (map nil #'funcall (after-update-hook optimizer)))
  
  (defun update-all-weights/sgd-nesterov (optimizer)
    (let ((accumulator (accumulator optimizer))
          (weight-deltas (weight-deltas optimizer))
          (learning-rate (learning-rate optimizer))
  
negative.code:                                  gradient-source n-new-inputs)
    (declare (type index n-new-inputs))
    (assert (eq (momentum-type optimizer) :normal))
    (assert (not (use-segment-derivatives-p optimizer)) ()
            "NORMALIZED-BATCH-GD-OPTIMIZER does not support ~
            USE-SEGMENT-DERIVATIVES-P.")
    (let ((accumulator (accumulator optimizer))
          (n-weight-uses-in-batch (n-weight-uses-in-batch optimizer))
          (weight-deltas (weight-deltas optimizer))
  