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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def combine_lists(d, keys=None, deepcopy=True):
 """combine lists of dicts Parameters d : dict or list[dict] keys : list keys to combine (all if None) deepcopy: bool deepcopy values Example ------- {'path_key': {'a': 1, 'split': {'x': [1, 2], 'y': [3, 4]}}} {'a': [2, 1]} """
  # noqa: E501
    if isinstance(d, list):
        init_list = True
        d = {'dummy_key843': d}
    else:
        init_list = False

    flattened = flatten(d, list_of_dicts=None)
    for key, value in list(flattened.items()):
        if keys is not None:
            try:
                if not key[-1] in keys:
                    continue
            except Exception:
                continue
        if not isinstance(value, list):
            continue
        if not all([is_dict_like(d) for d in value]):
            continue
        newd = {}
        for subdic in value:
            for subk, subv in subdic.items():
                if subk not in newd:
                    newd[subk] = []
                newd[subk].append(subv)
        flattened[key] = newd

    final = unflatten(flattened, list_of_dicts=None, deepcopy=deepcopy)

    if init_list:
        return list(final.values())[0]
    else:
        return final