def export_sheet(ss, sheet_id, export_format, export_path, sheet_name):
    """
    Exports a sheet, given export filetype and location. Allows export format 'csv', 'pdf', or 'xlsx'.
    :param ss:              initialized smartsheet client instance
    :param sheet_id:        int, required; sheet id
    :param export_format:   str, required; 'csv', 'pdf', or 'xlsx'
    :param export_path:     str, required; filepath to export sheet to
    :param sheet_name:      str, required; name of sheet exported
    :return:                str, indicating failure or success, with path, filename, extension
    """

    if export_format == 'csv':
        ss.Sheets.get_sheet_as_csv(sheet_id, export_path)
    elif export_format == 'xlsx':
        ss.Sheets.get_sheet_as_excel(sheet_id, export_path)
    elif export_format == 'pdf':                        # there is an optional paperSize parameter; default is A1
        ss.Sheets.get_sheet_as_pdf(sheet_id, export_path)

    if export_format == 'csv' or export_format == 'xlsx' or export_format == 'pdf':
        return 'Sheet exported to {}{}.{}'.format(export_path, sheet_name, export_format)
    else:
        return 'export_format \'{}\' is not valid. Must be \'csv\', \'pdf\', or \'xlsx\''.format(export_format)