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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 build_getter(validator, getter_namespace=None):
 """Create a getter function for retrieving values from the config cache. Getters will default to the DEFAULT namespace. """

    def proxy_register(key_name, default=UndefToken, help=None, namespace=None):
        name        = namespace or getter_namespace or config.DEFAULT
        namespace   = config.get_namespace(name)
        return proxy_factory.build(validator, namespace, key_name, default, help)

    return proxy_register