Was learning **Call, Apply, Bind** trio.

Then tried this:

```
Math.__proto__.sum = function(arg1){var res=0; for(i in arg1) res+=arg1[i]; return res; };
Math.sum([1,2,3])
//Output: "6function (arg1){var res=0; for(i in arg1) res+=arg1[i]; return res; }"

```

Why does this output contains function defination attached with the sum output?

How do we extend a built-in object like Math in a project with such utility methods and use it all over?

Thanks :)