'Returns
FileFormat'

def _get_reader(self):

    if (self.source == self.LOCAL_FILE):
        reader = FileFormat.get_reader(self.last_path())
        if (self.recent_paths and self.recent_paths[0].sheet):
            reader.select_sheet(self.recent_paths[0].sheet)
        return reader
    elif (self.source == self.URL):
        url = self.url_combo.currentText().strip()
        if url:
            return UrlReader(url)
