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_vec.m
    path of file: ./repos/PsPM/src/ext/VBA/stats&plots/spm_code
    
    the code of the file until where you have to start completion: function [vX] = spm_vec(varargin)
% vectorises a numeric, cell or structure array
% FORMAT [vX] = spm_vec(X);
% X  - numeric, cell or stucture array[s]
% vX - vec(X)
%__________________________________________________________________________
%
% e.g.:
% spm_vec({eye(2) 3}) = [1 0 0 1 3]'
%__________________________________________________________________________

    
function [vX] = spm_vec(varargin)
% vectorises a numeric, cell or structure array
% FORMAT [vX] = spm_vec(X);
% X  - numeric, cell or stucture array[s]
% vX - vec(X)
%__________________________________________________________________________
%
% e.g.:
% spm_vec({eye(2) 3}) = [1 0 0 1 3]'
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Karl Friston
% $Id: spm_vec.m 378 2016-11-07 13:17:49Z tmoser $

% initialise X and vX
%--------------------------------------------------------------------------
if nargin == 1
    X = varargin{1};
else
    X = varargin;
end