Personally, I prefer to use parenthesis to allow line continuation rather than backslashes. You can also technically omit the `+` signs since Python implicitly concatenates strings only separated by whitespace. So this could be:

```Python
robots_txt = (
    "User-agent: *\n"
    "Disallow: /cgi-bin/\n"
    "Disallow: /tmp/\n"
    "Disallow: /~joe/\n"
)
```