There're already a few katas about finding the difference of 2 arrays, and flattening an array.

Hi,

• The description is pretty bad about the wording ("length of a difference array of two given arrays"??) and, more importantly, doesn't describe the task correctly when inputs can be nested arrays... x/
• no random tests
• not enough tests
• you really should read those: https://github.com/Codewars/codewars.com/wiki/Kata-Creator and https://github.com/Codewars/codewars.com/wiki/Tutorial%3A-Create-Your-First-Kata, if you expect a kata to actually pass the beta process.

cheers