def print_prefixed_lines(lines: List[Tuple[str, Optional[str]]]) -> str:
    """Print lines specified like this: ["prefix", "string"]"""
    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
        )
    )
Print lines specified like this: ["prefix", "string"]