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: read_vtk_xml.m
    path of file: ./repos/spm/external/fieldtrip/fileio/private
    
    the code of the file until where you have to start completion: function data = read_vtk_xml(filename)

% READ_VTK_XML reads a XML-formatted vtk file containing points in 3D and
% connecting e
    
function output = base64decode(input)
%BASE64DECODE Decode Base64 string to a byte array.
%
%    output = base64decode(input)
%
% The function takes a Base64 string INPUT and returns a uint8 array
% OUTPUT. JAVA must be running to use this function. The result is always
% given as a 1-by-N array, and doesn't retrieve the original dimensions.
%
% See also base64encode
error(javachk('jvm'));
if ischar(input), input = uint8(input); end