<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_stats(self, nid=None):
 """Get statistics for class :type nid: str :param nid: This is the ID of the network to get stats from. This is optional and only to override the existing `network_id` entered when created the class """

        r = self.request(
            api_type="main",
            method="network.get_stats",
            nid=nid,
        )
        return self._handle_error(r, "Could not retrieve stats for class.")