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: vl_help.m
    path of file: ./repos/2015_Face_Detection/vlfeat/toolbox
    
    the code of the file until where you have to start completion: function vl_help(topic, varargin)
% VL_HELP   VLFeat toolbox builtin help
%   VL_HELP('doc') displays the HTML documentation in MATLAB
%   web-browser. VL_HELP('vl_function') displays the HTML
%   documentation relative to the specified funtion. VL_HELP('topic')
%   displays the HTML documentation relative to a particular 'topic'.
%
%   VL_HELP(..., 'ONLINE', true) uses the online documentation instead of
%   the local copy.
%
%   Example::
%     To get information about the library, a topic such as Fisher vectors,
%     or a function such as VL_FISHER(), use:
%        vl_help doc
%        vl_help fisher
%        vl_help vl_fisher

    
function vl_help(topic, varargin)
% VL_HELP   VLFeat toolbox builtin help
%   VL_HELP('doc') displays the HTML documentation in MATLAB
%   web-browser. VL_HELP('vl_function') displays the HTML
%   documentation relative to the specified funtion. VL_HELP('topic')
%   displays the HTML documentation relative to a particular 'topic'.
%
%   VL_HELP(..., 'ONLINE', true) uses the online documentation instead of
%   the local copy.
%
%   Example::
%     To get information about the library, a topic such as Fisher vectors,
%     or a function such as VL_FISHER(), use:
%        vl_help doc
%        vl_help fisher
%        vl_help vl_fisher
%
%   See also the <a href="matlab:vl_help('index')">core VLFeat
%   documentation</a>.

% Author: Andrea Vedaldi

% Copyright (C) 2013 Andrea Vedaldi
% All rights reserved.
%
% This file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).

if nargin == 0
  help vl_help ;
  return ;
end

opts.online = false ;
opts = vl_argparse(opts, varargin) ;

local = fullfile(vl_root, 'doc') ;
if opts.online
  prefix = 'http://www.vlfeat.org/doc' ;
else
  prefix = local ;
end