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: BoxPanel.m
    path of file: ./repos/erplab/studio_functions/GUI Layout Toolbox/layout/+uiextras
    
    the code of the file until where you have to start completion: classdef BoxPanel < uix.BoxPanel
    %uiextras.BoxPanel  Show one element inside a box panel
    %
    %   obj = uiextras.BoxPan
    
function obj = BoxPanel( varargin )
            
            % Call uix constructor
            obj@uix.BoxPanel( varargin{:} )
            
            % Add Enable property
            if ~isprop( obj, 'Enable' )
                p = addprop( obj, 'Enable' );
                p.GetMethod = @getEnable;
                p.SetMethod = @setEnable;
            end