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: horzcat.m
    path of file: ./repos/CanlabCore/CanlabCore/@image_vector
    
    the code of the file until where you have to start completion: function c = horzcat(varargin)
% Implements the horzcat ([a b]) operator on image_vector objects across voxels.
% Requires that each object has an equal number of columns and voxels
%
% :Usage:
% ::
%
%    function s = horzcat(varargin)
%
% :Examples:
% ::
%
%    c = [dat1 dat2];
%
% ..
%    Programmer Notes
%    Created 3/14/14 by Luke Chang
% ..

    
function c = horzcat(varargin)
% Implements the horzcat ([a b]) operator on image_vector objects across voxels.
% Requires that each object has an equal number of columns and voxels
%
% :Usage:
% ::
%
%    function s = horzcat(varargin)
%
% :Examples:
% ::
%
%    c = [dat1 dat2];
%
% ..
%    Programmer Notes
%    Created 3/14/14 by Luke Chang
% ..

error('This method is deprecated.  Use image_math instead.');

dat = [];
for i = 1:nargin
    %Check if image_vector object
    if ~isa(varargin{i}, 'image_vector')
        error('Input Data is not an image_vector object')
    end