def astype(self, dtype: np.dtype, /, *, copy: bool = True) -> "ConcatenatableArray":
        """Needed because xarray will call this even when it's a no-op"""
        if dtype != self.dtype:
            raise NotImplementedError()
        else:
            return self
Needed because xarray will call this even when it's a no-op
xarray/tests/arrays.py