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: root.m
    path of file: ./repos/CBIG/external_packages/matlab/non_default_packages/cifti-matlab-WashU-gradient/@xmltree
    
    the code of the file until where you have to start completion: function uid = root(tree)
% XMLTREE/ROOT Root Method
% FORMAT uid = root(tree)

    
function uid = root(tree)
% XMLTREE/ROOT Root Method
% FORMAT uid = root(tree)
% 
% tree   - XMLTree object
% uid    - UID of the root element of tree
%__________________________________________________________________________
%
% Return the uid of the root element of the tree.
%__________________________________________________________________________
% Copyright (C) 2002-2008  http://www.artefact.tk/

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

% Actually root is necessarily the element whos UID is 1, by
% construction. However, xml_parser should return a tree with a ROOT
% element with as many children as needed but only ONE *element* child
% who would be the real root (and this method should return the UID of
% this element).

uid = 1;

% Update:
% xml_parser has been modified (not as explained above) to handle the
% case when several nodes are at the top level of the XML.
% Example: <!-- beginning --><root>blah blah</root><!-- end