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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 register_preset(cls, name, preset):
 """ Register a preset instance with the class of the hub it corresponds to. This allows individual plugin objects to automatically register themselves with a preset by using a classmethod of their own with only the name of the preset to register with. """

        if cls._presets is None:
            cls._presets = {}
        cls._presets[name] = preset