Currently Cell is defined to be a tuple of 3 or 4: https://github.com/spglib/spglib/blob/develop/python/spglib/spglib.py#L70-L72

And some API would only give tuple of 3: https://github.com/spglib/spglib/blob/develop/python/spglib/spglib.py#L1425-L1428

And mypy would complain for such cases unless I explicitly check the length, I wouldn't say this is wrong because Cell is broader but narrowing it would be more convenient:

lattice, scaled_positions, numbers = spglib.refine_cell(self._cell, self._symprec, self._angle_tol)

>>> error: Too many values to unpack (3 expected, 4 provided)  [misc]