+/** \defgroup XBT_swag A O(1) set datatype
+ * \brief a O(1) set based on linked lists
+ *
+ * Warning, this module is done to be efficient and performs tons of
+ * cast and dirty things. So avoid using it unless you really know
+ * what you are doing. It is basically a fifo but with restrictions so that
+ * it can be used as a set. Any operation (add, remove, belongs) is O(1) and
+ * no call to malloc/free is done.
+ */
+