def __getitem__(self, idx):
        try:
            i, j = idx
            return self.blocks[i][j]
        except TypeError:
            return self.blocks[idx]
Test getting the thumbnail.
dataset/ETHPy150Open OP2/PyOP2/pyop2/petsc_base.py/Mat.__getitem__--crossover with--dataset/ETHPy150Open ofa/connect/open_connect/media/tests/test_models.py/ImageTest.test_get_thumbnail