Underscore.js has a very useful `map` function.

```
_.map([1, 2, 3], function(num){ return num * 3; });
=> [3, 6, 9]
_.map({one: 1, two: 2, three: 3}, function(num, key){ return num * 3; });
=> [3, 6, 9]

```

I am looking for a similar function that can iterate through nested objects, or deep mapping. After a ton of searching I can't really find this. What I can find is something to *pluck* a deep object, but not iterate through every value of a deep object.

Something like this:

```
deepMap({
  one: 1,
  two: [
    { foo: 'bar' },
    { foos: ['b', 'a', 'r', 's'] },
  ],
  three: [1, 2, 3]
}, function(val, key) {
  return (String(val).indexOf('b') > -1) ? 'bobcat' : val;
})

```

How would one do this?

### Sample Output

```
{
  one: 1,
  two: [
    { foo: 'bobcat' },
    { foos: ['bobcat', 'a', 'r', 's'] },
  ],
  three: [1, 2, 3]
}

```