fn pub mut buffer -> mut Buffer

fn pub mut next -> Option[Token]

fn pub inline move each(fun: fn (Token)) {
  loop {
    match self.next {
      case Some(v) -> fun.call(v)
      case _ -> break
    }
  }
}

fn pub move to_array -> Array[Token] {
  let tokens = []

  each(fn (v) { tokens.push(v) })
  tokens
}