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_ov_mesh.m
    path of file: ./repos/bspm/thirdparty/spm12/spm_orthviews
    
    the code of the file until where you have to start completion: function ret = spm_ov_mesh(varargin)
% Mesh tool - plugin for spm_orthviews
%
% This routine is a plugin to spm_orthviews. For general help about
% spm_orthviews and plugins type
%             help spm_orthviews
% at the MATLAB prompt.
%__________________________________________________________________________

    
function ret = spm_ov_mesh(varargin)
% Mesh tool - plugin for spm_orthviews
%
% This routine is a plugin to spm_orthviews. For general help about
% spm_orthviews and plugins type
%             help spm_orthviews
% at the MATLAB prompt.
%__________________________________________________________________________
% Copyright (C) 2017 Wellcome Trust Centre for Neuroimaging

% Torben Lund, Guillaume Flandin & Christian Gaser
% $Id: spm_ov_mesh.m 7183 2017-10-09 15:26:47Z guillaume $


switch lower(varargin{1})
    % Context menu and callbacks
    case 'context_menu'
        item0 = uimenu(varargin{3}, ...
            'Label', 'Mesh',...
            'UserData',...
                struct('style','','width',1,'id',varargin{2}));
        item1 = uimenu(item0,...
            'Label','Select mesh(es)...',...
            'Tag','menu',...
            'Callback',@(hObj,event) mesh_menu(hObj,event,varargin{2}));
        item2 = uimenu(item0,...
            'Label','Options');
        item2_1 = uimenu(item2,...
            'Label','Line style...',...
            'UserData',struct('str','Line style', 'field','style'),...
            'Callback',@(hObj,event) mesh_options(hObj,event,item0));
        item2_2 = uimenu(item2,...
            'Label','Line width...',...
            'UserData',struct('str','Line width', 'field','width'),...
            'Callback',@(hObj,event) mesh_options(hObj,event,item0));
        ret = item0;
    case 'display'
        if nargin < 2
            varargin{2} = spm_input('Select image', '!+1', 'e');
        end