my_map.rb

- [ ] should be identical and returns the same thing as ruby's [`map`](https://ruby-doc.org/core-2.6.4/Enumerable.html#method-i-map). ([Screenshot](https://gitlab.com/microverse/guides/projects/requirements_screenshots/raw/master/images/ruby/advanced_building_blocks_enumerable/my_map.png) from [Odin](https://www.theodinproject.com/courses/ruby-programming/lessons/advanced-building-blocks#assignment-2))
- [ ] returns a new array with the results of running block once for every element in enum.
```ruby
array = Array.new(100){rand(0...9)}
array.my_map(&block) == array.map(&block) # should return true
```
- [ ] returns an Enumerator if no block is given
```ruby
array.my_map == Enumerator # should return true
```