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: subsasgn.m
    path of file: ./repos/ExploreASL/External/SPMmodified/matlabbatch/@cfg_choice
    
    the code of the file until where you have to start completion: function item = subsasgn(item, subs, varargin)

% function item = subsasgn(item, subs, varargin)
% This function implements subsasgn for all classes derived from cfg_item.
% It relies on the capability of each class constructor to re-classify a
% struct object after a new value has been assigned to its underlying
% struct (This capability has to be implemented in the derived class).
% The structure of a configuration tree does not permit any arrays of
% cfg_item objects. Therefore, the only subscript reference and
% assignment within an cfg_item is a dot assignment to fields of this
% cfg_item. 
% Subscript references we have to deal with are:
% one level
% item.(field)   - i.e. struct('type',{'.'} ,'subs',{field})
%
% to be dealt with elsewhere
% item.(field){fidx}
% 
% In a future version, '()' and '{}' subscripts may be supported to
% access val fields of a cfg_item tree as if they were part of a
% harvested job. For cfg_branch objects (where dot assignments are used
% for val fields in their job tree) it is mandatory to index the job as a
% struct array to access harvested fields.
% This function is identical for all classes derived from cfg_item. A
% copy of it must be present in each derived class to be able to access
% derived fields.
%
% This code is part of a batch job configuration system for MATLAB. See 
%      help matlabbatch
% for a general overview.
%_______________________________________________________________________
% Copyright (C) 2007 Freiburg Brain Imaging

% Volkmar Glauche
% $Id: subsasgn.m 5678 2013-10-11 14:58:04Z volkmar $

rev = '$Rev: 5678 $'; %#ok

persistent local_mysubs_fields;
persistent par_class;
persistent par_fields;
if ~iscell(local_mysubs_fields)
    local_mysubs_fields = mysubs_fields;
    citem = class(item);
    switch citem
        case 'cfg_exbranch',
            par_class = 'cfg_branch';
            pf1 = subs_fields(item.cfg_branch);
            pf2 = subs_fields(cfg_item);

    
function item = subsasgn(item, subs, varargin)

% function item = subsasgn(item, subs, varargin)
% This function implements subsasgn for all classes derived from cfg_item.
% It relies on the capability of each class constructor to re-classify a
% struct object after a new value has been assigned to its underlying
% struct (This capability has to be implemented in the derived class).
% The structure of a configuration tree does not permit any arrays of
% cfg_item objects. Therefore, the only subscript reference and
% assignment within an cfg_item is a dot assignment to fields of this
% cfg_item. 
% Subscript references we have to deal with are:
% one level
% item.(field)   - i.e. struct('type',{'.'} ,'subs',{field})
%
% to be dealt with elsewhere
% item.(field){fidx}
% 
% In a future version, '()' and '{}' subscripts may be supported to
% access val fields of a cfg_item tree as if they were part of a
% harvested job. For cfg_branch objects (where dot assignments are used
% for val fields in their job tree) it is mandatory to index the job as a
% struct array to access harvested fields.
% This function is identical for all classes derived from cfg_item. A
% copy of it must be present in each derived class to be able to access
% derived fields.
%
% This code is part of a batch job configuration system for MATLAB. See 
%      help matlabbatch
% for a general overview.
%_______________________________________________________________________
% Copyright (C) 2007 Freiburg Brain Imaging

% Volkmar Glauche
% $Id: subsasgn.m 5678 2013-10-11 14:58:04Z volkmar $

rev = '$Rev: 5678 $'; %#ok

persistent local_mysubs_fields;
persistent par_class;
persistent par_fields;
if ~iscell(local_mysubs_fields)
    local_mysubs_fields = mysubs_fields;
    citem = class(item);
    switch citem
        case 'cfg_exbranch',
            par_class = 'cfg_branch';
            pf1 = subs_fields(item.cfg_branch);
            pf2 = subs_fields(cfg_item);
            par_fields = [pf1(:); pf2(:)]';
        case 'cfg_item',
            par_class = '';
            par_fields = {};
        otherwise
            par_class = 'cfg_item';
            par_fields = subs_fields(item.cfg_item);
    end