<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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 """

        worksheets = self.get_worksheets()
        return [(x.link[3].href.split('/')[-1], x.title.text)
            for x in worksheets.entry]