def insert_bigvul_comments(diff: str):
    """Insert comment lines in place of + and - in git diff patch."""
    lines = []
    for li in diff.splitlines():
        if len(li) == 0:
            continue
        if li[0] == "-":
            lines.append("//flaw_line_below:")
            li = li[1:]
        if li[0] == "+":
            lines.append("//fix_flaw_line_below:")
            li = "//" + li[1:]
        lines.append(li)
    return "\n".join(lines)