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_bioimage_mgrid.m
    path of file: ./repos/spm12/external/fieldtrip/fileio/private
    
    the code of the file until where you have to start completion: function [elec] = read_bioimage_mgrid(mgridfile)

% READ_BIOIMAGE_MGRID reads BioImage Suite *.mgrid files and converts them
% into a FieldTrip-compatible elec datatype structure with electrode
% positions in xyz coordinates (equals voxel coordinates in mm)
%

    
function [elec] = read_bioimage_mgrid(mgridfile)

% READ_BIOIMAGE_MGRID reads BioImage Suite *.mgrid files and converts them
% into a FieldTrip-compatible elec datatype structure with electrode
% positions in xyz coordinates (equals voxel coordinates in mm)
%
% Use as
%   elec = read_bioimage_mgrid(filename)
% where the filename has the .mgrid file extension
%
% See also FT_READ_SENS, FT_DATATYPE_SENS

% Copyright (C) 2017, Arjen Stolk & Sandon Griffin
%
% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
% for the documentation and details.
%
%    FieldTrip is free software: you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    FieldTrip is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
%
% $Id$

% define output
elec.label = {}; % N x 1 cell-array
elec.elecpos = []; % N x 3 matrix

% conditional variables
WaitForPos = 0;
WaitForDescript = 0;
WaitForDim = 0;

% open and read ascii-file line by line
fileline = 0;
fid = fopen_or_error(mgridfile,'r'); % open ascii-file
while fileline >= 0 % read line by line

  fileline = fgets(fid); % read a line
  if fileline > 0

    % grid number
    if contains(fileline,'# Electrode Grid ')
      GridNr = sscanf(fileline(strfind(fileline, 'Grid '):end