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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_mark(key=None):
 """Returns a decorator registering a mark class in the mark type registry. If no key is provided, the class name is used as a key. A key is provided for each core bqplot mark so that the frontend can use this key regardless of the kernel language. """

    def wrap(mark):
        name = key if key is not None else mark.__module__ + mark.__name__
        Mark.mark_types[name] = mark
        return mark
    return wrap