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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:
 async def execute_fetchall( self, sql: str, parameters: Iterable[Any] = None ) -> Iterable[sqlite3.Row]: """Helper to execute a query and return all the data."""

        if parameters is None:
            parameters = []
        return await self._execute(self._execute_fetchall, sql, parameters)