Goal: Implement the JavaScript `Array.concat` function in the type system. A type takes the two arguments. The output should be a new array that includes inputs in ltr order. For example: Source challenge: https://github.com/type-challenges/type-challenges/tree/main/questions/00533-easy-concat Reference explanation: https://github.com/ghaiklor/type-challenges-solutions/blob/main/en/easy-concat.md