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: spm_copy.m
    path of file: ./repos/ExploreASL/External/SPMmodified
    
    the code of the file until where you have to start completion: function spm_copy(source, dest, varargin)
% Copy file(s)
% FORMAT spm_copy(source, dest [,opts])
%__________________________________________________________________________
% Copyright (C) 2017 Wellcome Trust Centre for Neuroimaging

% Guillaume Flandin
% $Id: spm_copy.m 7121 2017-06-21 16:35:40Z guillaume $



    
function spm_copy(source, dest, varargin)
% Copy file(s)
% FORMAT spm_copy(source, dest [,opts])
%__________________________________________________________________________
% Copyright (C) 2017 Wellcome Trust Centre for Neuroimaging

% Guillaume Flandin
% $Id: spm_copy.m 7121 2017-06-21 16:35:40Z guillaume $


%-Source and destination
%--------------------------------------------------------------------------
source = cellstr(source);
if nargin < 2
    dest = pwd;
end