# Buggy code
def _tile_both_dataframes(cls, op):
    # if both of the inputs are DataFrames, axis is just ignored
    left, right = op.lhs, op.rhs
    df = op.outputs[0]

    nsplits, out_shape, left_chunks, right_chunks = align_dataframe_dataframe(
        left, right
    )
    out_chunk_indexes = itertools.product(*(range(s) for s in out_shape))

    out_chunks = []
    for idx, left_chunk, right_chunk in zip(
        out_chunk_indexes, left_chunks, right_chunks
    ):
        out_chunk = (
            op.copy()
            .reset_key()
            .new_chunk([left_chunk, right_chunk], shape=(np.nan, np.nan), index=idx)
        )
        out_chunks.append(out_chunk)

    new_op = op.copy()
    return new_op.new_dataframes(
        op.inputs,
        df.shape,
        nsplits=tuple(tuple(ns) for ns in nsplits),
        chunks=out_chunks,
        dtypes=df.dtypes,
        index_value=df.index_value,
        columns_value=df.columns,
    )


# Traceback (Exception)
In [28]: df = md.DataFrame(np.random.rand(10, 2))

In [29]: df + np.random.rand(10, 2)
---------------------------------------------------------------------------
Exception                                 Traceback (most recent call last)
<ipython-input-29-4a212df011a8> in <module>
----> 1 df + np.random.rand(10, 2)

~/Documents/mars_dev/mars/mars/dataframe/utils.py in wrapper(*args, **kwargs)
613     def wrapper(*args, **kwargs):
614         try:
--> 615             return func(*args, **kwargs)
616         except NotImplementedError:
617             return NotImplemented

~/Documents/mars_dev/mars/mars/dataframe/arithmetic/add.py in add(df, other, axis, level, fill_value)
33
34 def add(df, other, axis='columns', level=None, fill_value=None):
---> 35     other = wrap_sequence(other)
36     op = DataFrameAdd(axis=axis, level=level, fill_value=fill_value, lhs=df, rhs=other)
37     return op(df, other)

~/Documents/mars_dev/mars/mars/dataframe/utils.py in wrap_sequence(seq)
606
607     if isinstance(seq, (list, tuple, np.ndarray, TENSOR_TYPE)):
--> 608         seq = Series(seq)
609     return seq
610

~/Documents/mars_dev/mars/mars/dataframe/initializer.py in __init__(self, data, index, dtype, name, copy, chunk_size, gpu, sparse)
46             series = data
47         else:
---> 48             pd_series = pd.Series(data, index=index, dtype=dtype, name=name, copy=copy)
49             series = from_pandas_series(pd_series, chunk_size=chunk_size, gpu=gpu, sparse=sparse)
50         super(Series, self).__init__(series.data)

~/miniconda3/lib/python3.7/site-packages/pandas/core/series.py in __init__(self, data, index, dtype, name, copy, fastpath)
312                     data = data.copy()
313             else:
--> 314                 data = sanitize_array(data, index, dtype, copy, raise_cast_failure=True)
315
316                 data = SingleBlockManager(data, index, fastpath=True)

~/miniconda3/lib/python3.7/site-packages/pandas/core/internals/construction.py in sanitize_array(data, index, dtype, copy, raise_cast_failure)
727     elif subarr.ndim > 1:
728         if isinstance(data, np.ndarray):
--> 729             raise Exception("Data must be 1-dimensional")
730         else:
731             subarr = com.asarray_tuplesafe(data, dtype=dtype)

Exception: Data must be 1-dimensional

# Fixed code
def _tile_both_dataframes(cls, op):
    # if both of the inputs are DataFrames, axis is just ignored
    left, right = op.lhs, op.rhs
    df = op.outputs[0]

    nsplits, out_shape, left_chunks, right_chunks = align_dataframe_dataframe(
        left, right
    )
    out_chunk_indexes = itertools.product(*(range(s) for s in out_shape))

    out_chunks = []
    for idx, left_chunk, right_chunk in zip(
        out_chunk_indexes, left_chunks, right_chunks
    ):
        out_chunk = (
            op.copy()
            .reset_key()
            .new_chunk([left_chunk, right_chunk], shape=(np.nan, np.nan), index=idx)
        )
        out_chunks.append(out_chunk)

    new_op = op.copy()
    return new_op.new_dataframes(
        op.inputs,
        df.shape,
        nsplits=tuple(tuple(ns) for ns in nsplits),
        chunks=out_chunks,
        dtypes=df.dtypes,
        index_value=df.index_value,
        columns_value=df.columns_value,
    )