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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_connection(self, *args, **kwargs):
 """ Create a new connection, or return an existing one from the cache. Uses Fabric's current ``env.host_string`` and the URL to the Docker service. :param args: Additional arguments for the client constructor, if a new client has to be instantiated. :param kwargs: Additional keyword args for the client constructor, if a new client has to be instantiated. """

        key = env.get('host_string'), kwargs.get('base_url', env.get('docker_base_url'))
        default_config = _get_default_config(None)
        if default_config:
            if key not in self:
                self[key] = default_config
            return default_config.get_client()
        config = self.get_or_create_connection(key, self.configuration_class, *args, **kwargs)
        return config.get_client()