anchor.diff:                                                                           (/ 1.0 boids-cnt))
                                                        (entity-position boid))
                                 :cohesion)
  -                         0.4)
  +                         0.2)
           (p2dm:make-vector-2d))))
   
   (defun align (boid boids)
  
positive.code:          (too-close-cnt (length too-close)))
  
      (if (> too-close-cnt 0)
          (static-priority (ddv (entity-position boid)
                                (p2dm:subtract-vectors (entity-position boid)
                                                       (p2dm:scaled-vector (reduce #'p2dm:add-vectors too-close :key #'entity-position)
                                                                           (/ 1.0 too-close-cnt)))
                                :separation)
                           1.0)
          (p2dm:make-vector-2d))))
  
  (defun avoid-walls (boid)
  
negative.code: 
  (defparameter +max-boid-steering+ 60.0)
  (defparameter +max-boid-speed+ 60.0)
  (defparameter +min-boid-separation+ 30)
  
  (defparameter +min-boid-distance-to-game-area-boundary+ 30)
  
  