def gzip(filename):
    """ Gzip a file
    returns a 3-tuple with returncode (integer), terminal output (string)
    and the new filename.
    """

    ## run gzip
    retcode, output = sh('gzip %s' % filename)
    new_filename = filename+'.gz'

    return (retcode, output, new_filename)
Gzip a file
    returns a 3-tuple with returncode (integer), terminal output (string)
    and the new filename.