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: preprocess.m
    path of file: ./repos/automagic/preprocessing
    
    the code of the file until where you have to start completion: function [EEG, varargout] = preprocess(data, varargin)
% preprocess the input EEG 
%   [EEG, varargout] = preprocess(data, params)
%   where data is the EEGLAB data structure and params is an 
%   optional parameter specifying preprocessing parameters.

    
function [EEG, varargout] = preprocess(data, varargin)
% preprocess the input EEG 
%   [EEG, varargout] = preprocess(data, params)
%   where data is the EEGLAB data structure and params is an 
%   optional parameter specifying preprocessing parameters.
%   EEG is the output EEG after being preprocessed with additional fields.
%   varargout is a list of plots obtained during the preprocessing.
%
%   And example of the params where filtering parameters and clean_rawdata()
%   parameters are specified and other parameters are ommitted so that the 
%   deafult value is used, is as shown below:
%   params = struct('FilterParams', struct('notch', struct('freq', 50), ...
%                                        'high',  struct('freq', 0.5,...
%                                                        'order', []),...
%                                        'low',   struct('freq', 30,...
%                                                         'order',
%                                                         []))),...
%                   'CRDParams',    struct('ChannelCriterion',   0.85,...
%                                          'LineNoiseCriterion', 4,...
%                                          'BurstCriterion',     5,...
%                                          'WindowCriterion',    0.25, ...
%                                          'Highpass',           [0.25 0.75])
%                    )
%   
%   params must be a structure with optional fields 
%   'FilterParams', 'CRDParams', 'RPCAParams', 'MARAParams', 'PrepParams',
%   'InterpolationParams', 'EOGRegressionParams', 'EEGSystem',
%   'ChannelReductionParams', 'HighvarParams', 'MinvarParams', 'Settings', 'Detrend