def print_simple_annotation(code: str, linenos: Iterable[int]) -> None:
    """Print the lines in `code` with X for each line number in `linenos`."""
    for lineno, line in enumerate(code.splitlines(), start=1):
        print(" {} {}".format("X" if lineno in linenos else " ", line))
Print the lines in `code` with X for each line number in `linenos`.
tests/test_concurrency.py