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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 post_register_hook(self, verbosity=1):
 """Pull Docker images needed by processes after registering."""

        if not getattr(settings, 'FLOW_DOCKER_DONT_PULL', False):
            call_command('list_docker_images', pull=True, verbosity=verbosity)