# Buggy code
def shuffle(*arrays, **options):
    arrays = [convert_to_tensor_or_dataframe(ar) for ar in arrays]
    axes = options.pop("axes", (0,))
    if not isinstance(axes, Iterable):
        axes = (axes,)
    elif not isinstance(axes, tuple):
        axes = tuple(axes)
    random_state = check_random_state(options.pop("random_state", None)).to_numpy()
    if options:
        raise TypeError(
            "shuffle() got an unexpected keyword argument {0}".format(
                next(iter(options))
            )
        )

    max_ndim = max(ar.ndim for ar in arrays)
    axes = tuple(np.unique([validate_axis(max_ndim, ax) for ax in axes]))
    seeds = gen_random_seeds(len(axes), random_state)

    # verify shape
    for ax in axes:
        shapes = {ar.shape[ax] for ar in arrays if ax < ar.ndim}
        if len(shapes) > 1:
            raise ValueError("arrays do not have same shape on axis {0}".format(ax))

    op = LearnShuffle(
        axes=axes, seeds=tuple(seeds), output_types=get_output_types(*arrays)
    )
    shuffled_arrays = op(arrays)
    if len(arrays) == 1:
        return shuffled_arrays[0]
    else:
        return ExecutableTuple(shuffled_arrays)


# Traceback (AttributeError)
In [3]: import pandas as pd

In [4]: data = pd.DataFrame(np.arange(20).reshape((4, 5)) + 1, columns=['a', 'b', 'c', 'd', 'e'])

In [6]: df = md.DataFrame(data)

In [7]: df.groupby(['a','b']).size().execute()
Unexpected exception occurred in enter_build_mode.<locals>.inner.
Traceback (most recent call last):
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 353, in _wrapped
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 493, in inner
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/scheduler/graph.py", line 633, in prepare_graph
self._target_tileable_datas + fetch_tileables, tileable_graph)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 399, in _wrapped
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 493, in inner
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 350, in build
tileables, tileable_graph=tileable_graph)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 399, in _wrapped
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 493, in inner
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 263, in build
self._on_tile_failure(tileable_data.op, exc_info)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 302, in inner
raise exc_info[1].with_traceback(exc_info[2]) from None
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 243, in build
tiled = self._tile(tileable_data, tileable_graph)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 338, in _tile
return super()._tile(tileable_data, tileable_graph)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 203, in _tile
tds = on_tile(tileable_data.op.outputs, tds)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/scheduler/graph.py", line 615, in on_tile
return self.context.wraps(handler.dispatch)(first.op)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/context.py", line 69, in h
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/utils.py", line 399, in _wrapped
return func(*args, **kwargs)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/tiles.py", line 119, in dispatch
tiled = op_cls.tile(op)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/dataframe/groupby/aggregation.py", line 481, in tile
return cls._tile_with_tree(op)
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/dataframe/groupby/aggregation.py", line 412, in _tile_with_tree
index = out_df.index_value.to_pandas()
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/dataframe/core.py", line 283, in to_pandas
return self._index_value.to_pandas()
File "/Users/hekaisheng/Documents/mars_dev/mars/mars/dataframe/core.py", line 197, in to_pandas
sortorder=self._sortorder, names=self._names)
AttributeError: _sortorder

# Fixed code
def shuffle(*arrays, **options):
    arrays = [convert_to_tensor_or_dataframe(ar) for ar in arrays]
    axes = options.pop("axes", (0,))
    if not isinstance(axes, Iterable):
        axes = (axes,)
    elif not isinstance(axes, tuple):
        axes = tuple(axes)
    random_state = check_random_state(options.pop("random_state", None)).to_numpy()
    if options:
        raise TypeError(
            "shuffle() got an unexpected keyword argument {0}".format(
                next(iter(options))
            )
        )

    max_ndim = max(ar.ndim for ar in arrays)
    axes = tuple(np.unique([validate_axis(max_ndim, ax) for ax in axes]).tolist())
    seeds = gen_random_seeds(len(axes), random_state)

    # verify shape
    for ax in axes:
        shapes = {ar.shape[ax] for ar in arrays if ax < ar.ndim}
        if len(shapes) > 1:
            raise ValueError("arrays do not have same shape on axis {0}".format(ax))

    op = LearnShuffle(axes=axes, seeds=seeds, output_types=get_output_types(*arrays))
    shuffled_arrays = op(arrays)
    if len(arrays) == 1:
        return shuffled_arrays[0]
    else:
        return ExecutableTuple(shuffled_arrays)