function reverse<T>(items: T[]): T[] {
  var toreturn = []
  for (let i = items.length - 1; i >= 0; i--) {
    toreturn.push(items[i])
  }
  return toreturn
}

var sample = [1, 2, 3]
var reversed = reverse(sample)
console.log(reversed) // 3,2,1

// Safety!
reversed[0] = "1" // Error!
reversed = ["1", "2"] // Error!

reversed[0] = 1 // Okay
reversed = [1, 2] // Okay

/** A class definition with a generic parameter */
class Queue<T> {
  private data = []
  push(item: T) {
    this.data.push(item)
  }
  pop(): T | undefined {
    return this.data.shift()
  }
}

/** Again sample usage */
const queue = new Queue<number>()
queue.push(0)
queue.push("1") // ERROR : cannot push a string. Only numbers allowed

class Utility {
  reverse<T>(items: T[]): T[] {
    var toreturn = []
    for (let i = items.length - 1; i >= 0; i--) {
      toreturn.push(items[i])
    }
    return toreturn
  }
}