How to use the domutils.existsOne function in domutils

if(a === falseFunc || b === trueFunc){
		return b;
	}

	return function combine(elem){
		return a(elem) || b(elem);
	};
}

//:not, :has and :matches have to compile selectors
//doing this in lib/pseudos.js would lead to circular dependencies,
//so we add them here

var Pseudos     = require("./pseudos.js"),
    filters     = Pseudos.filters,
    existsOne   = DomUtils.existsOne,
    isTag       = DomUtils.isTag,
    getChildren = DomUtils.getChildren;


function containsTraversal(t){
	return t.some(isTraversal);
}

filters.not = function(next, token, options, context){
	var opts = {
	    	xmlMode: !!(options && options.xmlMode),
	    	strict: !!(options && options.strict)
	    };

	if(opts.strict){
		if(token.length > 1 || token.some(containsTraversal)){

return b;
	}

	return function combine(elem){
		return a(elem) || b(elem);
	};	
}

//:not and :has have to compile selectors
//doing this in lib/pseudos.js would lead to circular dependencies,
//so we add them here

var Pseudos     = require("./pseudos.js"),
    filters     = Pseudos.filters,
    isParent    = Pseudos.pseudos.parent,
    existsOne   = DomUtils.existsOne,
    getChildren = DomUtils.getChildren;

filters.not = function(next, select){
	var func = compileUnsafe(select);

	if(func === falseFunc) return next;
	if(func === trueFunc)  return falseFunc;

	return function(elem){
		return !func(elem) && next(elem);
	};
};

filters.has = function(next, selector){
	var func = compile(selector);

if(a === falseFunc || b === trueFunc){
		return b;
	}

	return function combine(elem){
		return a(elem) || b(elem);
	};
}

//:not, :has and :matches have to compile selectors
//doing this in lib/pseudos.js would lead to circular dependencies,
//so we add them here

var Pseudos     = require("./pseudos.js"),
    filters     = Pseudos.filters,
    existsOne   = DomUtils.existsOne,
    isTag       = DomUtils.isTag,
    getChildren = DomUtils.getChildren;


function containsTraversal(t){
	return t.some(isTraversal);
}

filters.not = function(next, token, options, context){
	var opts = {
	    	xmlMode: !!(options && options.xmlMode),
	    	strict: !!(options && options.strict)
	    };

	if(opts.strict){
		if(token.length > 1 || token.some(containsTraversal)){