def METHOD_NAME(self, os: str = None) -> pd.DataFrame:
    """system endpoint
    Args:
        os (str, optional): filter by the operating system. Defaults to None.
    Returns:
        pd.DataFrame: pandas dataframe
    """
    endpoint: str = path.join(self.endpoint, "system")
    params: Dict = {}
    if os is not None:
        params["os"] = os
    payload = requests.get(endpoint, params=params).json()["data"]
    df = self.__to_dataframe(payload, limit=self.limit)
    return df