anchor.diff:    "List of characters eligible for styles. This can be rebound if you desire more characters.")
   
   ;;; Classes
  +
  +(defstruct inhabitant
  +  (style #\.)
  +  (hipsterish-tendency 2/3))
   
   (defclass town-snapshot ()
     ((ticks :initform 0
  
positive.code:            :documentation "How long before the individuals know the clothing choice of their peers, measured in ticks.")
     (history :initarg :history
              :accessor town-history
              :documentation "The last iterations of the simulation, for use in computing certain future iterations.")))
  
  ;;; Class constructors
  
  
negative.code:   (when (zerop (ticks instance))
      (setf (aref (town-history instance) (mod (ticks instance) (period instance))) (population instance))))
  
  (defun make-foggy-town (population visibility &key (hipsterish-tendency 2/3) (styles #(#\# #\.)))
    (make-instance 'foggy-town
                   :population (generate-random-town population styles)
                   :visibility visibility
                   :hipsterish-tendency hipsterish-tendency
                   :styles styles))
  
  ;;; Common class methods
  
  (defmethod print-object ((object town-snapshot) stream)
  