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: preproc.m
    path of file: ./repos/fieldtrip/private
    
    the code of the file until where you have to start completion: function [dat, label, time, cfg] = preproc(dat, label, time, cfg, begpadding, endpadding)

% PREPROC applies various preprocessing steps on a single piece of EEG/MEG data
% that has been read from a data file.

    
function [dat, label, time, cfg] = preproc(dat, label, time, cfg, begpadding, endpadding)

% PREPROC applies various preprocessing steps on a single piece of EEG/MEG data
% that has been read from a data file.
%
% This low-level function serves as a subfunction for all FieldTrip modules that want
% to preprocess the data, such as FT_PREPROCESSING, FT_ARTIFACT_XXX,
% FT_TIMELOCKANALYSIS, etc. It ensures consistent handling of both MEG and EEG data
% and consistency in the use of all preprocessing configuration options.
%
% Use as
%   [dat, label, time, cfg] = preproc(dat, label, time, cfg, begpadding, end