def METHOD_NAME(self, timeout=2000):
    """
    Returns a nested dictionary containing all devices which have
    experienced a change at chassis level
    Args:
        timeout: Timeout in milliseconds (optional). If timeout == 0,
            this method will block until a change is detected.
    Returns:
        (bool, dict):
            - True if call successful, False if not;
            - A nested dictionary where key is a device type,
              value is a dictionary with key:value pairs in the
              format of {'device_id':'device_event'},
              where device_id is the device ID for this device and
                    device_event,
                         status='1' represents device inserted,
                         status='0' represents device removed.
              Ex. {'fan':{'0':'0', '2':'1'}, 'sfp':{'11':'0'}}
                  indicates that fan 0 has been removed, fan 2
                  has been inserted and sfp 11 has been removed.
    """
    ret, port_dict = self._sfp_list[0].get_transceiver_change_event(timeout)
    ret_dict = {"sfp": port_dict}
    return ret, ret_dict