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: in_tess_vtk.m
    path of file: ./repos/brainstorm3/toolbox/io
    
    the code of the file until where you have to start completion: function TessMat = in_tess_vtk(TessFile)
% IN_TESS_VTK: Read Visualization Toolkit .vtk mesh files
%
% USAGE:  TessMat = in_tess_vtk(TessFile);
%
% INPUT: 
%     - TessFile : full path to a tesselation file
% OUTPUT:
%     - TessMat:  Brainstorm tesselation structure
% FORMAT:
%     ASCII file with the following structure:
%     - Header line 1: "# vtk DataFile Version ???"
%     - Header line 2: "surface file"
%     - Header line 3: "ASCII"
%     - Header line 4: "DATASET POLYDATA"
%     - Header line 5: "POINTS <nVertices>  float"
%     - Vertices     : nVertices lines ("x y z"), values in miliimeters
%     - Header line 6: "POLYGONS <nFaces> <nValues>"

    
function TessMat = in_tess_vtk(TessFile)
% IN_TESS_VTK: Read Visualization Toolkit .vtk mesh files
%
% USAGE:  TessMat = in_tess_vtk(TessFile);
%
% INPUT: 
%     - TessFile : full path to a tesselation file
% OUTPUT:
%     - TessMat:  Brainstorm tesselation structure
% FORMAT:
%     ASCII file with the following structure:
%     - Header line 1: "# vtk DataFile Version ???"
%     - Header line 2: "surface file"
%     - Header line 3: "ASCII"
%     - Header line 4: "DATASET POLYDATA"
%     - Header line 5: "POINTS <nVertices>  float"
%     - Vertices     : nVertices lines ("x y z"), values in miliimeters
%     - Header line 6: "POLYGONS <nFaces> <nValues>"
%     - Faces        : nFaces lines ("nvert vertex1 vertex2 vertex3")
%
% SEE ALSO: in_tess

% @=============================================================================
% This function is part of the Brainstorm software:
% https://neuroimage.usc.edu/brainstorm
% 
% Copyright (c) University of Southern California & McGill University
% This software is distributed under the terms of the GNU General Public License
% as published by the Free Software Foundation. Further details on the GPLv3
% license can be found at http://www.gnu.org/copyleft/gpl.html.
% 
% FOR RESEARCH PURPOSES ONLY. THE SOFTWARE IS PROVIDED "AS IS," AND THE
% UNIVERSITY OF SOUTHERN CALIFORNIA AND ITS COLLABORATORS DO NOT MAKE ANY
% WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF
% MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, NOR DO THEY ASSUME ANY
% LIABILITY OR RESPONSIBILITY FOR THE USE OF THIS SOFTWARE.
%
% For more information type "brainstorm license" at command prompt.
% =============================================================================@
%
% Authors: Francois Tadel, 2012

% Open tesselation file
fid = fopen(TessFile, 'r');
if fid < 0
    error(['Cannot open file ', TessFile])
end