/**
* \param l a list
* \return the head of \a l.
+ *
+ * Returns NULL if the list is empty.
*/
XBT_INLINE xbt_fifo_item_t xbt_fifo_get_first_item(xbt_fifo_t l)
{
/**
* \param l a list
* \return the tail of \a l.
+ *
+ * Returns NULL if the list is empty.
*/
XBT_INLINE xbt_fifo_item_t xbt_fifo_get_last_item(xbt_fifo_t l)
{
/**
* \param i a bucket
* \return the bucket that comes next
+ *
+ * Returns NULL if \a i is the tail of the list.
*/
XBT_INLINE xbt_fifo_item_t xbt_fifo_get_next_item(xbt_fifo_item_t i)
{
/**
* \param i a bucket
* \return the bucket that is just before \a i.
+ *
+ * Returns NULL if \a i is the head of the list.
*/
XBT_INLINE xbt_fifo_item_t xbt_fifo_get_prev_item(xbt_fifo_item_t i)
{