code: def print_prefixed_lines(lines: List[Tuple[str, Optional[str]]]) -> str:
      
      existing_lines = [line for line in lines if line[1] is not None]
      pad_len = reduce(lambda pad, line: max(pad, len(line[0])), existing_lines, 0)
      return "\n".join(
          map(
              lambda line: line[0].rjust(pad_len) + line[1], existing_lines  # type:ignore
          )
      )
docs: Print lines specified like this: ["prefix", "string"]