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

    def wrap(axis):
        name = key if key is not None else axis.__module__ + axis.__name__
        BaseAxis.axis_types[name] = axis
        return axis
    return wrap