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: m2tcustom.m
    path of file: ./repos/matlab2tikz/src
    
    the code of the file until where you have to start completion: function [value] = m2tcustom(handle, varargin)
    % M2TCUSTOM creates user-defined options for matlab2tikz output
    %
    % M2TCUSTOM can be used to create, get and set a properly formatted data 
    % structure to customize the conversion of MATLAB figures to TikZ using 
    % matlab2tikz. In particular, it allows to:
    %
    %   * add blocks of LaTeX/TikZ code around any HG object,
    %   * add blocks of comments around any HG object,
    %   * add TikZ options to any HG object,
    %   * add LaTeX/TikZ code inside some HG objects (e.g. axes),
    %   * provide a custom handler to convert a particular HG object.
    %
    % Note that this provides advanced functionality. Only very basic 
    % sanity checks are performed such that injudicious use may produce
    % broken TikZ figures!
    %
    % It is HIGHLY recommended that you are comfortable with:
    %
    %   * writing pgfplots, TikZ and LaTeX code, 
    %   * using the
    
function (either as |char| or
    % function handle) that will be called as
    %
    %     [m2t, str] = feval(handler, m2t, handle, custom)
    %
    % such that the expected function signature is:
    %
    %     function [m2t, str] = handler(m2t, handle, custom)
    %  
    % where |m2t| is an undocumented/unstable data structure,
    %       |str| is a char containing TikZ code representing the 
    %             HG object |handle| as generated by your handler,
    %       |custom| is a structure as returned by |m2tcustom|
    %             from which you only need to handle |extraOptions|,
    %             |codeInsideFirst| and |codeInsideLast| when applicable.
    % A particularly useful value for |customHandler| is 'drawNothing',
    % which remove the object from the output.
    %
    %       
    % Example: 
    % --------
    %
    % Executing the following MATLAB code fragment:
    %
    %    figure;
    %    plot(1:10);
    %    EOL = sprintf('\n');
    %    m2tCustom(gca, 'codeBefore'      , ['<codeBefore>' EOL]     , ...
    %                   'codeAfter'       , ['<codeAfter>'  EOL]     , ...
    %                   'commentsBefore'  ,  '<commentsBefore>'      , ...
    %                   'commentsAfter'   ,  '<commentsAfter>'       , ...
    %                   'codeInsideFirst' , ['<codeInsideFirst>' EOL], ...
    %                   'codeInsideLast'  , ['<codeInsideLast>'  EOL], ...
    %                   'extraOptions'    ,  '<extraOptions>');
    %
    %    matlab2tikz('test.tikz')
    % 
    % Should result in a |test.tikz| file with contents that look somewhat
    % like this:
    %
    %       \begin{tikzpicture}
    %           %<commentsBefore>
    %           <codeBefore>
    %           \begin{axis}[..., <extraOptions>]
    %               <codeInsideFirst>
    %               \addplot{...};
    %               <codeInsideLast>
    %           \end