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: sepia_handle_panel_R2s_NLLS.m
    path of file: ./repos/sepia/gui_func/panel/R2s_method
    
    the code of the file until where you have to start completion: %% h = sepia_handle_panel_qsm_CFS(hParent,h,position)
%
% Input
% --------------
% hParent       : parent handle of this panel
% h             : global structure contains all handles
% position      : position of this panel
%
% Output
% --------------
% h             : global structure contains all new and other handles
%
% Description: This GUI function creates a panel for CFS method
%
% Kwok-shing Chan @ DCCN
% k.chan@donders.ru.nl
% Date created: 1 June 2018
% Date modified: 4 April 2020
%
%
function h = sepia_handle_panel_R2s_NLLS(hParent,h,position)

%% set default values
% menuFitType = {'Magnitude','Complex','Mixed'};

%% Tooltips

%% layout of the panel
nrow        = 4;
rspacing    = 0.01;
ncol        = 2;
cspacing    = 0.01;
[height,bottom,width,left] = sepia_layout_measurement(nrow,rspacing,ncol,cspacing);

%% Parent handle of CFS panel ch
    
function creates a panel for CFS method
%
% Kwok-shing Chan @ DCCN
% k.chan@donders.ru.nl
% Date created: 1 June 2018
% Date modified: 4 April 2020
%
%
function h = sepia_handle_panel_R2s_NLLS(hParent,h,position)

%% set default values
% menuFitType = {'Magnitude','Complex','Mixed'};

%% Tooltips

%% layout of the panel
nrow        = 4;
rspacing    = 0.01;
ncol        = 2;
cspacing    = 0.01;
[height,bottom,width,left] = sepia_layout_measurement(nrow,rspacing,ncol,cspacing);

%% Parent handle of CFS panel children

h.r2s.panel.nlls = uipanel(hParent,...
    'Title','Non-linear least square (NLLS)',...
    'position',position,...
    'backgroundcolor',get(h.fig,'color'),'Visible','off');
        
%% Children of CFS panel
    
    panelParent = h.r2s.panel.nlls;

    % width of each element in a functional column, in normalised unit
    wratio = 0.5;
    
    % row 1, col 1
%     % text|edit field pair: S0 parameter
%     [h.r2s.nlls.text.fit,h.r2s.nlls.popup.fit] = sepia_construct_text_popup(...
%         panelParent,'Fitting type:', menuFitType, [left(1) bottom(1) width height], wratio);

    h.r2s.nlls.checkbox.isParallel = uicontrol('Parent',panelParent,...
        'Style','checkbox',...
        'String','Enable parallel computing (parfor)',...
        'units','normalized','position',[left(1) bottom(1) width height]);

%% set tooltips
% set(h.r2s.trapezoidal.text.s0,      'Tooltip',tooltip.r2s.trapezoidal.s0);

%% set callbacks


end