Map vs Collect vs Each

TODO

map vs map!

[142] pry(main)> nums = [2, 3, 4, 5, 6]

=> [2, 3, 4, 5, 6]

[143] pry(main)> nums.map { |num| num*2 }

=> [4, 6, 8, 10, 12]

[144] pry(main)> nums

=> [2, 3, 4, 5, 6]

# Map! manipulates origional array

[142] pry(main)> nums

=> [2, 3, 4, 5, 6]

[145] pry(main)> nums.map! { |num| num*2 }

=> [4, 6, 8, 10, 12]

[146] pry(main)> nums

=> [4, 6, 8, 10, 12]