-@param[in] trace_class Trace class to which to add the listener.
-@param[in] listener Listener to add to \p trace_class.
-@param[in] data User data passed when \p listener is called.
-@returns A unique numeric identifier for this listener
- on success (0 or greater), or a negative value
- on error.
+@param[in] trace_class Trace class to which to add the
+ listener.
+@param[in] listener Listener to add to \p trace_class.
+@param[in] listener_removed Remove listener called when \p listener
+ is removed from \p trace_class, or
+ \c NULL if you don't need a remove
+ listener.
+@param[in] data User data passed when \p listener or
+ \p listener_removed is called.
+@returns A unique numeric identifier for this
+ listener on success (0 or greater), or a
+ negative value on error.