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: ft_trialfun_trial.m
    path of file: ./repos/spm12/external/fieldtrip/trialfun
    
    the code of the file until where you have to start completion: function [trl, event] = ft_trialfun_trial(cfg)

% FT_TRIALFUN_TRIAL creates a trial definition that corresponds to the
% events that are returned by FT_READ_EVENT with type='trial'
%
% You can use this function as follows
%   cfg           = [];   
%   cfg.dataset   = string, containing filename or directory
%   cfg.trialfun  = 'ft_trialfun_trial';
%   cfg           = definetrial(cfg);
%   data          = preprocessing(cfg);
%
% See also FT_DEFINETRIAL, FT_PREPROCESSING

% Copyright (C) 2012, Donders Centre for Cognitive Neuroimaging, Nijmegen, NL
%
% 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/>.
%
% $Id$

if isfield(cfg, 'event')
  % for BCI applications events should be specified in the cfg

    
function [trl, event] = ft_trialfun_trial(cfg)

% FT_TRIALFUN_TRIAL creates a trial definition that corresponds to the
% events that are returned by FT_READ_EVENT with type='trial'
%
% You can use this function as follows
%   cfg           = [];   
%   cfg.dataset   = string, containing filename or directory
%   cfg.trialfun  = 'ft_trialfun_trial';
%   cfg           = definetrial(cfg);
%   data          = preprocessing(cfg);
%
% See also FT_DEFINETRIAL, FT_PREPROCESSING

% Copyright (C) 2012, Donders Centre for Cognitive Neuroimaging, Nijmegen, NL
%
% 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/>.
%
% $Id$

if isfield(cfg, 'event')
  % for BCI applications events should be specified in the cfg
  % to prevent reading the same events many times
  event = cfg.event;
else
  event = ft_read_event(cfg.dataset);
end