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: GraphBU.m
    path of file: ./repos/BRAPH-2/braph2/graphs
    
    the code of the file until where you have to start completion: classdef GraphBU < Graph
	%GraphBU is a binary undirected graph.
	% It is a subclass of <a href="matlab:help Graph">Graph</a>.
	%
	% In a binary undirected (BU) graph, the edges are undirected and can be 
	%  either 0 (absence of connection) or 1 (existence of connection).
	% The connectivity matrix is symmetric.
	%
	% The list of GraphBU properties is:
	%  <strong>1</strong> <strong>ELCLASS</strong> 	ELCLASS (constant, string) is the class of the % % % .
	%  <strong>2</strong> <strong>NAME</strong> 	NAME (constant, string) is the name of the binary undirected graph.
	%  <strong>3</strong> <strong>DESCRIPTION</strong> 	DESCRIPTION (constant, string) is the description of the binary undirected graph.
	%  <strong>4</strong> <strong>TEMPLATE</strong> 	TEMPLATE (parameter, item) is the template of the binary undirected graph.
	%  <strong>5</strong> <strong>ID</strong> 	ID (data, string) i
    
function check_out = existsProp(prop)
			%EXISTSPROP checks whether property exists in binary undirected graph/error.
			%
			% CHECK = GraphBU.EXISTSPROP(PROP) checks whether the property PROP exists.
			%
			% Alternative forms to call this method are:
			%  CHECK = G.EXISTSPROP(PROP) checks whether PROP exists for G.
			%  CHECK = Element.EXISTSPROP(G, PROP) checks whether PROP exists for G.
			%  CHECK = Element.EXISTSPROP(GraphBU, PROP) checks whether PROP exists for GraphBU.
			%
			% Element.EXISTSPROP(PROP) throws an error if the PROP does NOT exist.
			%  Error id: [BRAPH2:GraphBU:WrongInput]
			%
			% Alternative forms to call this method are:
			%  G.EXISTSPROP(PROP) throws error if PROP does NOT exist for G.
			%   Error id: [BRAPH2:GraphBU:WrongInput]
			%  Element.EXISTSPROP(G, PROP) throws error if PROP does NOT exist for G.
			%   Error id: [BRAPH2:GraphBU:WrongInput]
			%  Element.EXISTSPROP(GraphBU, PROP) throws error if PROP does NOT exist for GraphBU.
			%   Error id: [BRAPH2:GraphBU:WrongInput]
			%
			% Note that the Element.EXISTSPROP(G) and Element.EXISTSPROP('GraphBU')
			%  are less computationally efficient.
			%
			% See also getProps, existsTag.
			
			check = prop >= 1 && prop <= 40 && round(prop) == prop; %CET: Computational Efficiency Trick
			
			if nargout == 1
				check_out = check;
			elseif ~check
				error( ...
					['BRAPH2' ':GraphBU:' 'WrongInput'], ...
					['BRAPH2' ':GraphBU:' 'WrongInput' '\n' ...
					'The value ' tostring(prop, 100, ' ...') ' is not a valid prop for GraphBU.'] ...
					)
			end