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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 get_app(self):
 """Get current app from Flast stack to use. This will allow to ensure which Redis connection to be used when accessing Redis connection public methods via plugin. """

        # First see to connection stack
        ctx = connection_stack.top
        if ctx is not None:
            return ctx.app

        # Next return app from instance cache
        if self.app is not None:
            return self.app

        # Something went wrong, in most cases app just not instantiated yet
        # and we cannot locate it
        raise RuntimeError(
            'Flask application not registered on Redis instance '
            'and no applcation bound to current context')