def get_start_end_date(df, feature, format="%Y-%m-%d  %H:%M:%S"):
    """
    Returns the start and end date of a time series

    Args
        df: DataFrame consisting of the time series
        feature: Name of the time series feature. The column should be of type np.datetime64
        format: String format in which start and end date will be returned
    """
    start_date = df[feature].min().strftime(format="%Y-%m-%d  %H:%M:%S")
    end_date = df[feature].max().strftime(format="%Y-%m-%d  %H:%M:%S")
    return start_date, end_date