define(['../lang/toNumber'], function (toNumber) {
/**
* Get sign of the value.
*/
function sign(val) {
var num = toNumber(val);
if (num === 0) return num; // +0 and +0 === 0
if (isNaN(num)) return num; // NaN
return num < 0? -1 : 1;
}
return sign;
});