//why is it called partial?
Function.prototype.partialApply = function(){
 var func = this;
 args = Array.prototype.slice.call(arguments); //why slice?
 return function(){
 return func.apply(this, args.concat(//what is apply doing in this case?
 Array.prototype.slice.call(arguments)//special arguments variable, what are we doing with it?
 ));
 };
};
//example of usage
//create a function that converts numbers to hex values
function nums2hex() {
 function componentToHex(component) {
 var hex = component.toString(16);
 // make sure the return value is 2 digits, i.e. 0c or 12
 if (hex.length == 1) {
 return "0" + hex;
 }
 else {
 return hex;
 }
 }
 return Array.prototype.map.call(arguments,
 componentToHex).join('');
}

var myOUI = 123;
var example = nums2hex.partialApply(myOUI);//now can we  chain because partialApply is a prototype of function object?
console.log(example());// '7b'