A map takes an array and a mapping function and produces a new array containing
the result of applying the mapping function to each value in the
original array, as visualised below:

```
  +-+      +--+
  |A|      |A'|
  | |      |  |
  |B| ---> |B'|
  | |      |  |
  |C|      |C'|
  +-+      +--+
```

----

# Task

Convert the following code from a for-loop to Array#map:

```js
function doubleAll(numbers) {
  var result = []
  for (var i = 0; i < numbers.length; i++) {
    result.push(numbers[i] * 2)
  }
  return result
}

module.exports = doubleAll
```

## Arguments

* numbers: An Array of 1 to 20 Integers between 0 and 9

## Conditions

* Your solution should use Array.prototype.map()
* Do not use any for/while loops or Array.prototype.forEach.
* Do not create any unecessary functions e.g. helpers.

## Resources

* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map