:x: Problematic code:
$ cat >> system.py <<EOF """Module docstring.""" "system" EOF
:heavy_check_mark: Correct code:
$ cat >> system.py <<EOF """Module docstring.""" value = "system" EOF
Used when a string is used as a statement (which of course has no effect). This is a particular case of W0104 with its own message so you can easily disable it if you're using those strings as documentation, instead of comments.