void TRACE_category_set(smx_process_t proc, const char *category);
char *TRACE_category_get(smx_process_t proc);
void TRACE_category_unset(smx_process_t proc);
-void TRACE_msg_category_set(smx_process_t proc, m_task_t task);
/* declaration of instrumentation functions from msg_task_instr.c */
char *TRACE_task_container(m_task_t task, char *output, int len);