javascript: indesign find by grep

gistfile1

function find_by_grep (grep_keyword, paragraph_style, app_document) {
	var app_doc = app_document || app.activeDocument;
	app.findChangeGrepOptions.includeLockedLayersForFind = false;
	app.findChangeGrepOptions.includeLockedStoriesForFind = false;
	app.findChangeGrepOptions.includeHiddenLayers = false;
	app.findChangeGrepOptions.includeMasterPages = false;
	app.findChangeGrepOptions.includeFootnotes = false;

	// app.findChangeTextOptions.caseSensitive = true;
	// app.findChangeTextOptions.wholeWord = true;

	app.findGrepPreferences = app.changeGrepPreferences = null;	
	app.findGrepPreferences.appliedParagraphStyle = paragraph_style || null;
	app.findGrepPreferences.findWhat = grep_keyword;
	var my_founds = app_doc.findGrep();
	// app.changeGrepPreferences.changeTo = NothingEnum.nothing;
	// mySelection.changeGrep();
	app.findGrepPreferences = app.changeGrepPreferences = null;
	return my_founds;
};