/**
 * Allow using namespace.
 * http://blogger.ziesemer.com/2008/05/javascript-namespace-function.html
 */
String.prototype.namespace = function(separator) {
	var ns = this.split(separator || '.'),
    	o = window,
    	i,
    	len;
	for (i = 0, len = ns.length; i < len; i++) {
		o = o[ns[i]] = o[ns[i]] || {};
	}
	return o;
};

/**
 * Check if the class exists or not
 * Usage:
 * 
 * 	'x.y.z'.namespace();
 * 	if (!'x.y.z'.isClassExist()) {
 * 		x.y.z = function(...) { ... };
 * 		
 * 		// Declare more prototypes of class here ...
 * 	}
 * 
 * @since 2.0.9
 */
String.prototype.isClassExist = function() {
	return eval('typeof ' + this) == 'function';
};