def merge_result(res):
    """
    Merges all items in `res` into a list.

    This command is used when sending a command to multiple nodes
    and they result from each node should be merged into a single list.
    """

    if not isinstance(res, dict):
        raise ValueError("Value should be of dict type")

    result = set([])

    for _, v in res.items():
        for value in v:
            result.add(value)

    return list(result)