anchor.diff:  
   (defun make-forest (n-class datum-dim datamatrix target
                       &key (n-tree 100) (bagging-ratio 0.1) (max-depth 5) (min-region-samples 1)
  -                      (n-trial 10) (gain-test #'entropy))
  +                      (n-trial 10) (gain-test #'entropy) (remove-sample-indices? t))
     (let ((forest (%make-forest
                    :n-tree n-tree
                    :bagging-ratio bagging-ratio
  
positive.code: 
  (defun make-dtree (n-class datum-dim datamatrix target
                     &key (max-depth 5) (min-region-samples 1) (n-trial 10)
                       (gain-test #'entropy) sample-indices)
    (let* ((len (if sample-indices
                    (length sample-indices)
                    (array-dimension datamatrix 0)))
  
negative.code:                  :max-depth max-depth :min-region-samples min-region-samples
                   :n-trial n-trial
                   :gain-test gain-test
                   :remove-sample-indices? remove-sample-indices?
                   :tmp-arr1 (make-array len :element-type 'fixnum :initial-element 0)
                   :tmp-index1 0
                   :tmp-arr2 (make-array len :element-type 'fixnum :initial-element 0)
  