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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 run(app: web.Application):
 """ Runs the application in an async context. This function will block indefinitely until the application is shut down. Args: app (web.Application):
 The Aiohttp Application as created by `create_app()` """

    host = app['config']['host']
    port = app['config']['port']

    # starts app. run_app() will automatically start the async context.
    web.run_app(app, host=host, port=port)