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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _generate_report_all(self):
        '''Generate report for all subfolders contained by self.folder_id.'''
        assert self.workbook is not None
        count = 0

        # Do all subfolders
        for sid in self.folders.subfolders(self.folder_id, self.user):
            count += 1
            self._generate_for_subfolder(sid)

        if count == 0:
            print("I: empty workbook created: no subfolders found")