import Buffer from "buffer"
import String from "string"
let fib = j => {
  // set-up minimal, growable buffer
  let buf = Buffer.make(j * 2)
  let mut fnow = 0, fnext = 1
  for (let mut n = 0; n <= j; n += 1) {
    if (n == 0 || n == 1) {
      Buffer.addChar(' ', buf)
      Buffer.addString(toString(n), buf)
    } else {
      let tempf = fnow + fnext
      fnow = fnext
      fnext = tempf
      Buffer.addChar(' ', buf)
      Buffer.addString(toString(fnext), buf)
    }
  }
  // stringify buffer and return
  Buffer.toString(buf)
}
let output = fib(20)
print(output)