anchor.diff:  ;;;; phenex.lisp
   
   (in-package #:phenex)
  +
  +(defconstant EPSILON 1e-9)
   
   (defmacro bind (&body body)
     `(multiple-value-bind ,@body))
  
positive.code: 		   (destructuring-bind (yi . xi)
  		       yx
  		     (if (= (funcall h xi) yi)
  			 (* wi (/ err (- 1 err)))
  			 wi)))
  	       cases weights)))
      (values (normalize edited-weights)
  
negative.code: 		    (setf w w+
  			  (svref h k) h-fn
  			  (svref z k) (log (/ (- 1 h-err)
  					      (max h-err EPSILON))
  					   2))
  		    (incf k)))))
      (cons h z)))
  