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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 init_publisher(app):
 """Calling this with your flask app as argument is required for the publisher decorator to work. """

    @app.context_processor
    def inject_links():
        return {
            'websub_self_url': stack.top.websub_self_url,
            'websub_hub_url': stack.top.websub_hub_url,
            'websub_self_link': stack.top.websub_self_link,
            'websub_hub_link': stack.top.websub_hub_link,
        }