# Buggy code
def __init__(
    self,
    df,
    by,
    axis,
    level,
    as_index,
    sort,
    group_keys,
    squeeze,
    idx_name,
    drop,
    **kwargs,
):
    self._axis = axis
    self._idx_name = idx_name
    self._df = df
    self._query_compiler = self._df._query_compiler
    self._index = self._query_compiler.index
    self._columns = self._query_compiler.columns
    self._by = by
    self._drop = drop

    if (
        level is None
        and not isinstance(by, type(self._query_compiler))
        and is_list_like(by)
    ):
        # This tells us whether or not there are multiple columns/rows in the groupby
        self._is_multi_by = all(obj in self._df for obj in self._by) and axis == 0
    else:
        self._is_multi_by = False
    self._level = level
    self._kwargs = {
        "level": level,
        "sort": sort,
        "as_index": as_index,
        "group_keys": group_keys,
        "squeeze": squeeze,
    }
    self._kwargs.update(kwargs)


# Traceback (ValueError)
Traceback (most recent call last):
File "/localdisk/gashiman/omniscripts/taxi/taxibench_pandas.py", line 190, in <module>
query(query_df)
File "/localdisk/gashiman/omniscripts/taxi/taxibench_pandas.py", line 95, in q3
return transformed.groupby(['passenger_count','pickup_datetime'])[['passenger_count','pickup_datetime']].count()['passenger_count']
File "/nfs/site/proj/scripting_tools/gashiman/modin/modin/pandas/groupby.py", line 249, in __getitem__
return SeriesGroupBy(self._default_to_pandas(lambda df: df.__getitem__(key)))
File "/nfs/site/proj/scripting_tools/gashiman/modin/modin/pandas/groupby.py", line 535, in _default_to_pandas
return self._df._default_to_pandas(groupby_on_multiple_columns)
File "/nfs/site/proj/scripting_tools/gashiman/modin/modin/pandas/base.py", line 227, in _default_to_pandas
result = op(pandas_obj, *args, **kwargs)
File "/nfs/site/proj/scripting_tools/gashiman/modin/modin/pandas/groupby.py", line 533, in groupby_on_multiple_columns
return f(df.groupby(by=by, axis=self._axis, **self._kwargs), **kwargs)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/generic.py", line 7894, in groupby
**kwargs
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/groupby/groupby.py", line 2522, in groupby
return klass(obj, by, **kwds)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/groupby/groupby.py", line 391, in __init__
mutated=self.mutated,
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/groupby/grouper.py", line 652, in _get_grouper
if not isinstance(gpr, Grouping)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/groupby/grouper.py", line 347, in __init__
raise ValueError("Grouper for '{}' not 1-dimensional".format(t))
ValueError: Grouper for '<class 'pandas.core.frame.DataFrame'>' not 1-dimensional

# Fixed code
def __init__(
    self,
    df,
    by,
    axis,
    level,
    as_index,
    sort,
    group_keys,
    squeeze,
    idx_name,
    drop,
    **kwargs,
):
    self._axis = axis
    self._idx_name = idx_name
    self._df = df
    self._query_compiler = self._df._query_compiler
    self._index = self._query_compiler.index
    self._columns = self._query_compiler.columns
    self._by = by
    self._drop = drop

    if level is None and is_list_like(by) or isinstance(by, type(self._query_compiler)):
        # This tells us whether or not there are multiple columns/rows in the groupby
        self._is_multi_by = (
            isinstance(by, type(self._query_compiler)) and len(by.columns) > 1
        ) or (
            not isinstance(by, type(self._query_compiler))
            and all(obj in self._df for obj in self._by)
            and axis == 0
        )
    else:
        self._is_multi_by = False
    self._level = level
    self._kwargs = {
        "level": level,
        "sort": sort,
        "as_index": as_index,
        "group_keys": group_keys,
        "squeeze": squeeze,
    }
    self._kwargs.update(kwargs)