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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 merge_result(res):
 """ Merge 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)