Converts pandas.DataFrame values into list
        :param df: pandas.DataFrame
        :return: list

def df2list(df):
        """
        Converts pandas.DataFrame values into list
        :param df: pandas.DataFrame
        :return: list
        """
        for column in df:
            df[column] = df[column].astype(object).where(df[column].notnull(), None)
        return df.to_dict(orient='records')