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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 save_image(image, filename=None):
 """ Saves a Docker image from the remote to a local files. For performance reasons, uses the Docker command line client on the host, generates a gzip-tarball and downloads that. :param image: Image name or id. :type image: unicode :param filename: File name to store the local file. If not provided, will use ``<image>.tar.gz`` in the current working directory. :type filename: unicode """

    local_name = filename or '{0}.tar.gz'.format(image)
    cli.save_image(image, local_name)