def __getitem__(self, idx):
        """Return :class:`Mat` block with row and column given by ``idx``
        or a given row of blocks."""
        try:
            i, j = idx
            return self.blocks[i][j]
        except __HOLE__:
            return self.blocks[idx]
dataset/ETHPy150Open OP2/PyOP2/pyop2/petsc_base.py/Mat.__getitem__