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: mergetable.m
    path of file: ./repos/fieldtrip/private
    
    the code of the file until where you have to start completion: function t3 = mergetable(t1, t2, key)

% MERGETABLE merges two tables where the rows and columns can be partially
% overlapping or different. Values from the 2nd input have precedence in case the
% same row and column is also present in the 1st.
%
% Use as
%   t3 = mergetable(t1, t2)
% or
%   t3 = mergetable(t1, t2, key)
%
% See also MERGESTRUCT, JOIN, INNERJOIN, OUTERJOIN

% Copyright (C) 2019-2022, Robert Oostenveld
%
% 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/>.
%
% $Id$

% deal with the easy cases
if isequal(t1, t2)
  t3 = t1;
  return
elseif isempty(t1)

    
function t3 = mergetable(t1, t2, key)

% MERGETABLE merges two tables where the rows and columns can be partially
% overlapping or different. Values from the 2nd input have precedence in case the
% same row and column is also present in the 1st.
%
% Use as
%   t3 = mergetable(t1, t2)
% or
%   t3 = mergetable(t1, t2, key)
%
% See also MERGESTRUCT, JOIN, INNERJOIN, OUTERJOIN

% Copyright (C) 2019-2022, Robert Oostenveld
%
% 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/>.
%
% $Id$

% deal with the easy cases
if isequal(t1, t2)
  t3 = t1;
  return
elseif isempty(t1)
  t3 = t2;
  return
elseif isempty(t2)
  t3 = t1;
  return
end