anchor.diff:  (defclass font-app (base-app)
     ((font-loader :accessor font-loader)
      (bukva :accessor bukva)
  -   (candidate :accessor candidate)))
  +   (candidate :accessor candidate :initform '())))
   
   (defmethod setup ((app font-app))
     (set-background 0.25 0.63 0.54))
  
positive.code: (defmethod draw ((app font-app))
    (clear)
    (set-color 0.0 0.0 0.0)
    (draw-string (font-loader app) (bukva app) 2000 -3500 :filled nil :size 250))
  
  (defmethod exit ((app font-app))
    (zpb-ttf:close-font-loader (font-loader app)))
  
negative.code: 	(chromosome-length 10))
      (setf (font-loader app) (zpb-ttf:open-font-loader #P"/Library/Fonts/Arial.ttf"))
      (setf (bukva app) "Б")    
  
      ;; initialization
      (setf *population* (initialize-population population-size chromosome-length))
      ;; evaluation
      ;; selection
      ;; crossover
      ;; mutation
      (setf (candidate app)
  	  (loop for coords across (chromosome->coordinates (first *population*))
  	     collect (coords->curve coords)))
      (run app)
  ))
  
  (defun initialize-population (population-size chromosome-length)
  