Only give scalar options that have a varying range

def _get_scalar_names(self, limit=None):
        """Only give scalar options that have a varying range"""
        names = []
        if limit == 'point':
            inpnames = list(self.input_dataset.point_arrays.keys())
        elif limit == 'cell':
            inpnames = list(self.input_dataset.cell_arrays.keys())
        else:
            inpnames = self.input_dataset.scalar_names
        for name in inpnames:
            arr = self.input_dataset.get_scalar(name)
            rng = self.input_dataset.get_data_range(name)
            if arr is not None and arr.size > 0 and (rng[1]-rng[0] > 0.0):
                names.append(name)
        try:
            self._last_scalars = names[0]
        except IndexError:
            pass
        return names