stream method
Implementation
Stream<(A, B)> stream() async* {
final from = _from(_expressions.toList());
final decode1 = _expressions.$1._decode;
final decode2 = _expressions.$2._decode;
final task = _context._dialect.select(SelectStatement._(from));
await for (final row in _context._query(task)) {
yield (decode1(row) as A, decode2(row) as B);
}
}