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: length.m
    path of file: ./repos/CBIG/external_packages/matlab/default_packages/cifti-matlab/@xmltree
    
    the code of the file until where you have to start completion: function l = length(tree,r)
% XMLTREE/LENGTH Length Method
% FORMAT l = length(tree,r)
% 
% tree - XMLTree object
% r    - 'real' if present, returns the real number of nodes in the
%         tree (deleted nodes aren't populated)
% l    - length of the XML tree (number of nodes)
%__________________________________________________________________________
%
% Return the number of nodes of an XMLTree object.
%__________________________________________________________________________
% Copyright (C) 2002-2011  http://www.artefact.tk/

% Guillaume Flandin
% $Id: length.m 4460 2011-09-05 14:52:16Z guillaume $


%error(nargchk(1,2,nargin));

% Return the full number of nodes once allocated
l = length(tree.tree);


    
function l = length(tree,r)
% XMLTREE/LENGTH Length Method
% FORMAT l = length(tree,r)
% 
% tree - XMLTree object
% r    - 'real' if present, returns the real number of nodes in the
%         tree (deleted nodes aren't populated)
% l    - length of the XML tree (number of nodes)
%__________________________________________________________________________
%
% Return the number of nodes of an XMLTree object.
%__________________________________________________________________________
% Copyright (C) 2002-2011  http://www.artefact.tk/

% Guillaume Flandin
% $Id: length.m 4460 2011-09-05 14:52:16Z guillaume $


%error(nargchk(1,2,nargin));

% Return the full number of nodes once allocated
l = length(tree.tree);

% Substract the number of deleted nodes to the previous length
if nargin == 2
    if strcmp(r,'real')
        ll = 0;
        for i=1:l
            if ~strcmp(tree.tree{i}.type,'deleted')
                ll = ll + 1;
            end