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: ExporterBrainAtlasXLS.m
    path of file: ./repos/BRAPH-2/braph2/src/atlas
    
    the code of the file until where you have to start completion: classdef ExporterBrainAtlasXLS < Exporter
	%ExporterBrainAtlasXLS exports a brain atlas to an XLS/XLSX file.
	% It is a subclass of <a href="matlab:help Exporter">Exporter</a>.
	%
	% A Brain Atlas Exporter in XLS Files (ExporterBrainAtlasXLS) exports a brain atlas to an XLS/XLSX file.
	%
	% The list of ExporterBrainAtlasXLS properties is:
	%  <strong>1</strong> <strong>ELCLASS</strong> 	ELCLASS (constant, string) is the class of the brain atlas exporter in XLS.
	%  <strong>2</strong> <strong>NAME</strong> 	NAME (constant, string) is the name of the brain atlas exporter in XLS.
	%  <strong>3</strong> <strong>DESCRIPTION</strong> 	DESCRIPTION (constant, string) is the description of the brain atlas exporter in XLS.
	%  <
    
function prop_number = getPropNumber(varargin)
			%GETPROPNUMBER returns the property number of brain atlas exporter in XLS.
			%
			% N = ExporterBrainAtlasXLS.GETPROPNUMBER() returns the property number of brain atlas exporter in XLS.
			%
			% N = ExporterBrainAtlasXLS.GETPROPNUMBER(CATEGORY) returns the property number of brain atlas exporter in XLS
			%  of category CATEGORY
			%
			% Alternative forms to call this method are:
			%  N = EX.GETPROPNUMBER([CATEGORY]) returns the property number of the brain atlas exporter in XLS EX.
			%  N = Element.GETPROPNUMBER(EX) returns the property number of 'EX'.
			%  N = Element.GETPROPNUMBER('ExporterBrainAtlasXLS') returns the property number of 'ExporterBrainAtlasXLS'.
			%
			% Note that the Element.GETPROPNUMBER(EX) and Element.GETPROPNUMBER('ExporterBrainAtlasXLS')
			%  are less computationally efficient.
			%
			% See also getProps, Category.
			
			%CET: Computational Efficiency Trick
			
			if nargin == 0
				prop_number = 13;
				return
			end