+/** Pointer to an activity object */
+typedef s4u_Activity* sg_activity_t;
+/** Pointer to a constant activity object */
+typedef const s4u_Activity* const_sg_activity_t;
+
+/** Pointer to an activity set object */
+typedef s4u_ActivitySet* sg_activity_set_t;
+/** Pointer to a constant activity set object */
+typedef const s4u_ActivitySet* const_sg_activity_set_t;
+