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: cat_batch_cat.m
    path of file: ./repos/cat12
    
    the code of the file until where you have to start completion: function cat_batch_cat(namefile,cat_defaults)
% wrapper for using batch mode (see cat_batch_cat.sh)
%
% namefile      - array of file names or text file with file names
% cat_defaults  - use this default file instead of cat_defaults.m
%
% ______________________________________________________________________
%
% Christian Gaser, Robert Dahnke
% Structural Brain Mapping Group (https://neuro-jena.github.io)
% Departments of Neurology and Psychiatry
% Jena University Hospital
% ______________________________________________________________________
% $Id$

 %#ok<*TRYNC>
 

    
function cat_batch_cat(namefile,cat_defaults)
% wrapper for using batch mode (see cat_batch_cat.sh)
%
% namefile      - array of file names or text file with file names
% cat_defaults  - use this default file instead of cat_defaults.m
%
% ______________________________________________________________________
%
% Christian Gaser, Robert Dahnke
% Structural Brain Mapping Group (https://neuro-jena.github.io)
% Departments of Neurology and Psychiatry
% Jena University Hospital
% ______________________________________________________________________
% $Id$

 %#ok<*TRYNC>
 
if nargin < 1
  fprintf('Syntax: cat_batch_cat(namefile,cat_defaults)\n');
  return
end

addpath(fileparts(which(mfilename)))

[t,pid] = system('echo $$');
fprintf('cat_batch_cat: \n  PID = %s\n\n',pid);

global defaults cat matlabbatch %#ok<NUSED>

spm_get_defaults;

if nargin < 2
    cat_get_defaults;
else
    if isempty(cat_defaults)
        cat_get_defaults;
    else
        fprintf('Use defaults in %s.\n',cat_defaults);
        [pp, name] = spm_fileparts(cat_defaults);
        clear cat_defaults
        oldpath = pwd;
        if ~isempty(pp), cd(pp); end