List what worksheet keys exist

        Returns a list of tuples of the form:
            (WORKSHEET_ID, WORKSHEET_NAME)
        You can then retrieve the specific WORKSHEET_ID in the future by
        constructing a new GSpreadsheet(worksheet=WORKSHEET_ID, ...)

def list_worksheets(self):
        """
        List what worksheet keys exist

        Returns a list of tuples of the form:
            (WORKSHEET_ID, WORKSHEET_NAME)
        You can then retrieve the specific WORKSHEET_ID in the future by
        constructing a new GSpreadsheet(worksheet=WORKSHEET_ID, ...)
        """
        worksheets = self.get_worksheets()
        return [(x.link[3].href.split('/')[-1], x.title.text)
            for x in worksheets.entry]