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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 as_set(obj):
 """ Convert obj into a set, returns None if obj is None. """

    if obj is None or isinstance(obj, collections.Set):
        return obj

    if not isinstance(obj, collections.Iterable):
        return set((obj,))
    else:
        return set(obj)