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: cluster_surf_batch.m
    path of file: ./repos/CanlabCore/CanlabCore/Visualization_functions
    
    the code of the file until where you have to start completion: function surf_handles = cluster_surf_batch(varargin)
% :Usage:
% ::
%
%    surf_handles = cluster_surf_batch(varargin)
%
% :Examples:
% ::
%
%    % Single-map visualization
%    P2 = threshold_imgs('rob_tmap_0001.img',tinv(1-.005,12),15,'pos');
%    cluster_surf_batch(P2);
%    surf_handles = cluster_surf_batch(cl,{[1 0 0]},cl2);
%
%    % Two maps with overlap
%    surf_handles = cluster_surf_batch(cl,{[1 0 0] [0 1 0] [1 1 0]},cl2);


surf_handles = [];

% Input arguments
% cl, then colors, then cl2, in that order

if length(varargin) == 0
    disp('Choose thresholded image to get clusters from.')

    
function surf_handles = cluster_surf_batch(varargin)
% :Usage:
% ::
%
%    surf_handles = cluster_surf_batch(varargin)
%
% :Examples:
% ::
%
%    % Single-map visualization
%    P2 = threshold_imgs('rob_tmap_0001.img',tinv(1-.005,12),15,'pos');
%    cluster_surf_batch(P2);
%    surf_handles = cluster_surf_batch(cl,{[1 0 0]},cl2);
%
%    % Two maps with overlap
%    surf_handles = cluster_surf_batch(cl,{[1 0 0] [0 1 0] [1 1 0]},cl2);


surf_handles = [];

% Input arguments
% cl, then colors, then cl2, in that order

if length(varargin) == 0
    disp('Choose thresholded image to get clusters from.')
    imgname = spm_get(1);
    cl = mask2clusters(imgname);

elseif isstruct(varargin{1})
    cl = varargin{1};

elseif isstr(varargin{1})
    cl = mask2clusters(varargin{1});

else
    error('You must input either nothing, an image name, or a cluster structure.');
end