<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def server_info_cb(self, context, server_info_p, userdata):
 """Retrieves the default sink and calls request_update"""

        server_info = server_info_p.contents
        self.request_update(context)