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_tmsi_poly5.m
    path of file: ./repos/fieldtrip/fileio/private
    
    the code of the file until where you have to start completion: function [out] = read_tmsi_poly5(filename, varargin)

% READ_TMSI_POLY5
%
% Use as
%   hdr = read_tmri_poly5(filename)
%   dat = read_tmsi_poly5(filename, hdr, begblock, endblock)
%
% This implementat
    
function in a struct array, and
%   - Allow for a selection of channels to be read, reducing memory footprint, and calibration step
%
% This program 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.

needhdr = (nargin==1);
needdat = (nargin>1);

if needdat
  signal = varargin{1};
  begblock = varargin{2};
  endblock = varargin{3};
end

if numel(varargin)==4
  chanindx = varargin{4};
else
  chanindx = [];
end

fid = fopen_or_error(filename, 'rb');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% read the header
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if needhdr
  pos = 31;
  fseek(fid,pos,'bof');
  version = fread(fid,1,'int16');
  if version == 203
    frewind(fid);
    signal.header.FID                   = fread(fid,31,'uchar');
    signal.header.VersionNumber         = fread(fid, 1,'int16');
  else % version 204
    frewind(fid);
    signal.header.FID                   = fread(fid,32,'uchar');
    signal.header.VersionNumber         = fread(fid, 1,'int16');
  end