<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def session_info(self, session_id=None):
 """Get information on session. If session_id is None, the default, then return information about this session. If a session ID is given, then get information about that session. Arguments: session_id -- Id of session to get info for, if not this session. Return: Dictionary of session information. """

        if not session_id:
            if not self.started():
                return []
            session_id = self._sid
        status, data = self._rest.get_request('sessions', session_id)
        return data