+(defun agentset-breed (agentset)
+ (cond
+ ((eql agentset :turtles) :turtles)
+ ((eql agentset :patches) :patches)
+ ((and (listp agentset) (eql :agentset (car agentset))) (second agentset))
+ (t (error "Doesn't seem to be an agentset: ~A" agentset))))
+
+(defun list->agentset (list breed)
+ (append (list :agentset breed) list))