def count_null(column=None, index=None):
    """
    Get total number of null values in a DplyFrame,
    one or more rows of DplyFrame,
    or one or more columns of DplyFrame
    :param column: one column name or one list of column names of a DplyFrame
    :param index: one row name or one list of row names of a DplyFrame
    :return: a nonnegative integer
    """

    def _count_null(d1, column=None, index=None):
        if column is not None:
            return d1.pandas_df[column].isna().sum().sum()
        if index is not None:
            return d1.pandas_df.loc[index].isna().sum().sum()
        return d1.pandas_df.isnull().sum().sum()

    return lambda d1: _count_null(d1, column, index)