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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 sadd(self, key, *members):
 """Add the specified members to the set stored at key. Specified members that are already a member of this set are ignored. If key does not exist, a new set is created before adding the specified members. An error is returned when the value stored at key is not a set. Returns :data:`True` if all requested members are added. If more than one member is passed in and not all members are added, the number of added members is returned. .. note:: **Time complexity**: ``O(N)`` where ``N`` is the number of members to be added. :param key: The key of the set :type key: :class:`str`, :class:`bytes` :param members: One or more positional arguments to add to the set :type key: :class:`str`, :class:`bytes` :returns: Number of items added to the set :rtype: bool, int """

        return self._execute([b'SADD', key] + list(members), len(members))