(defvar *current-id* 0)
(defvar *turtles* nil)
+(defvar *patches* nil)
(defvar *myself* nil)
(defvar *self* nil)
(defvar *dimensions* nil)
(defvar *topology* :torus)
+(defvar *ticks* nil)
(defstruct turtle who color heading xcor ycor)
+(defstruct patch color xcor ycor)