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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 fetchall(self):
 """Fetch all the rows"""

        self._check_executed()
        if self._rows is None:
            return ()
        if self.rownumber:
            result = self._rows[self.rownumber:]
        else:
            result = self._rows
        self.rownumber = len(self._rows)
        return result