system.dataset.exportExcel(filename, showHeaders, dataset[, nullsEmpty])
String filename - A suggested filename to save as.
boolean showHeaders - If true (1), the spreadsheet will include a header row.
Object dataset - A sequence of datasets, one for each sheet in the resulting workbook.
Boolean nullsEmpty - If True (1), the spreadsheet will leave cells with NULL values empty, instead of allowing Excel to provide a default value like 0. Defaults to False. [Optional]
String - The path to the saved file, or None if the action was canceled by the user.