Function lift

when.js:106–113

* Lift the supplied function, creating a version of f that returns * promises, and accepts promises as arguments. * @param {function} f * @returns {Function} version of f that returns promises

(f)

	 * @returns {Function} version of f that returns promises
	 */
	function lift(f) {
		return function() {
			for(var i=0, l=arguments.length, a=new Array(l); i<l; ++i) {
				a[i] = arguments[i];
			}
			return apply(f, this, a);
		};
	}

	/**
	 * Call f in a future turn, with the supplied args, and return a promise