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: children.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 child = children(tree,uid)
% XMLTREE/CHILDREN Return children's UIDs of node uid
% FORMAT child = children(tree,uid)
%
% tree   - a tree
% uid    - uid of the element
% child  - array of the UIDs of children of node uid

    
function child = children(tree,uid)
% XMLTREE/CHILDREN Return children's UIDs of node uid
% FORMAT child = children(tree,uid)
%
% tree   - a tree
% uid    - uid of the element
% child  - array of the UIDs of children of node uid
%__________________________________________________________________________
%
% Return UID's of children of node uid
%__________________________________________________________________________
% Copyright (C) 2002-2011  http://www.artefact.tk/

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

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

child = [];
uid = uid(:);
l = length(tree);
for i=1:length(uid)
    if uid(i) > 0 && uid(i) <= l
        if strcmp(tree.tree{uid(i)}.type,'element')
            child = [child tree.tree{uid(i)}.contents];
        end