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_sections.m
    path of file: ./repos/ExploreASL/External/SPMmodified
    
    the code of the file until where you have to start completion: function spm_sections(xSPM,hReg,img)
% Rendering of regional effects [SPM{.}] on orthogonal sections
% FORMAT spm_sections(xSPM,hReg,img)
%

    
function spm_sections(xSPM,hReg,img)
% Rendering of regional effects [SPM{.}] on orthogonal sections
% FORMAT spm_sections(xSPM,hReg,img)
%
% xSPM  - structure containing details of excursion set (see spm_getSPM)
% hReg  - handle of MIP register
% img   - filename of background image
%__________________________________________________________________________
%
% spm_sections is called by spm_results_ui and uses variable img to
% create three orthogonal sections through a background image.
% Regional foci from the selected xSPM are rendered on this image.
%__________________________________________________________________________
% Copyright (C) 1994-2011 Wellcome Trust Centre for Neuroimaging

% John Ashburner
% $Id: spm_sections.m 4199 2011-02-10 20:07:17Z guillaume $


if ~nargin, [SPM,xSPM] = spm_getSPM; end
if nargin < 2, hReg = []; end
if nargin < 3 || isempty(img)
    [img, sts] = spm_select(1,'image','Select image for rendering on');
    if ~sts, return; end