+(defmethod shared-initialize ((sequencer sequencer) slot-names
+ &key (constraints nil constraintsp))
+ (call-next-method)
+ (when constraintsp
+ (setf (slot-value sequencer 'constraints)
+ (mapcar (lambda (constraint)
+ (mapcar (lambda (name)
+ (ensure-sequencer-item sequencer name))
+ constraint))
+ (reverse constraints))))
+ sequencer)
+