XBT_PUBLIC(MSG_error_t) MSG_task_get(m_task_t * task, m_channel_t channel);
XBT_PUBLIC(MSG_error_t) MSG_task_get_with_time_out(m_task_t * task, m_channel_t channel,
XBT_PUBLIC(MSG_error_t) MSG_task_get(m_task_t * task, m_channel_t channel);
XBT_PUBLIC(MSG_error_t) MSG_task_get_with_time_out(m_task_t * task, m_channel_t channel,