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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 first_key(res):
 """ Returns the first result for the given command. If more then 1 result is returned then a `RedisClusterException` is raised. """

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

    if len(res.keys()) != 1:
        raise RedisClusterException("More then 1 result from command")

    return list(res.values())[0]