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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 proxy_for(widget):
 """Create a proxy for a Widget :param widget: A gtk.Widget to proxy This will raise a KeyError if there is no proxy type registered for the widget type. """

    proxy_type = widget_proxies.get(widget.__class__)
    if proxy_type is None:
        raise KeyError('There is no proxy type registered for %r' % widget)
    return proxy_type(widget)