You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cfg_run_gzip_files.m
    path of file: ./repos/spm/matlabbatch/cfg_basicio
    
    the code of the file until where you have to start completion: function out = cfg_run_gzip_files(job)
% Run gzip on a list of files.
%
% This code is part of a batch job configuration system for MATLAB. See 

    
function out = cfg_run_gzip_files(job)
% Run gzip on a list of files.
%
% This code is part of a batch job configuration system for MATLAB. See 
%      help matlabbatch
% for a general overview.
%_______________________________________________________________________
% Copyright (C) 2007 Freiburg Brain Imaging

% Volkmar Glauche
% $Id: cfg_run_gzip_files.m 7499 2018-11-28 11:57:34Z guillaume $

rev = '$Rev: 7499 $'; %#ok

if isempty(job.outdir) || isempty(job.outdir{1})
    out = gzip(job.files);
else
    out = gzip(job.files, job.outdir{1});
end