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: coherenceGUI.m
    path of file: ./repos/acycle/code/guicode
    
    the code of the file until where you have to start completion: function varargout = coherenceGUI(varargin)
% COHERENCEGUI MATLAB code for coherenceGUI.fig
%      COHERENCEGUI, by itself, creates a new COHERENCEGUI or raises the existing
%      singleton*.
%
%      H = COHERENCEGUI returns the handle to a new COHERENCEGUI or the handle to
%      the existing singleton*.
%
%      COHERENCEGUI('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in COHERENCEGUI.M with the given input arguments.
%
%      COHERENCEGUI('Property','Value',...) creates a new COHERENCEGUI or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before coherenceGUI_OpeningFcn 
    
function popupmenu2_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu2 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from popupmenu2
coherence_update;
guidata(hObject,handles)

% --- Executes during object creation, after setting all properties.
function popupmenu2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to popupmenu2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end