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: attributes.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8/@xmltree
    
    the code of the file until where you have to start completion: function varargout = attributes(varargin)
% XMLTREE/ATTRIBUTES Method (handle attributes of an element node)
% FORMAT varargout = attributes(varargin)
% 
% tree    - XMLTree object
% method  - 'set','get','add','del' or 'length'
% uid     - the UID of an element node
% n       - indice of the attribute
% key     - string key="..."
% val     - string ...="val"
% attr    - cell array of struct(key,val) or just struct(key,val)
% l       - number of attributes of the element node uid
%
%     tree = attributes(tree,'set',uid,n,key,val)
%     attr = attributes(tree,'get',uid[,n])
%     tree = attributes(tree,'add',uid,key,val)
%     tree = attributes(tree,'del',uid[,n])
%     l    = attributes(tree,'length',uid)
%_______________________________________________________________________
%

    
function varargout = attributes(varargin)
% XMLTREE/ATTRIBUTES Method (handle attributes of an element node)
% FORMAT varargout = attributes(varargin)
% 
% tree    - XMLTree object
% method  - 'set','get','add','del' or 'length'
% uid     - the UID of an element node
% n       - indice of the attribute
% key     - string key="..."
% val     - string ...="val"
% attr    - cell array of struct(key,val) or just struct(key,val)
% l       - number of attributes of the element node uid
%
%     tree = attributes(tree,'set',uid,n,key,val)
%     attr = attributes(tree,'get',uid[,n])
%     tree = attributes(tree,'add',uid,key,val)
%     tree = attributes(tree,'del',uid[,n])
%     l    = attributes(tree,'length',uid)
%_______________________________________________________________________
%
% Handle attributes of an element node.
% The tree parameter must be in input AND in output for 'set', 'add' and
% 'del' methods.
%_______________________________________________________________________
% Copyright (C) 2002-2008  http://www.artefact.tk/

% Guillaume Flandin <guillaume@artefact.tk>
% $Id: attributes.m 1460 2008-04-21 17:43:18Z guillaume $

error(nargchk(3,6,nargin));
tree = varargin{1};
if ~ischar(varargin{2}) || ...
   ~any(strcmp(varargin{2},{'set','get','add','del','length'}))
    error('[XMLTree] Unknown method.');
end