function retrieve(values) {
	        for (var i = 0, len = arguments.length; i < len; i++) {
	            if (arguments[i] != null) {
	                return arguments[i];
	            }
	        }
	    }
If value1 is not null, then return value1, otherwise judget rest of values.
Low performance.
@memberOf module:zrender/core/util
@return {*} Final value