> This will help when someone writes something like `b'abcd'[2] == b'c'`

What if someone writes line[-1] == 0 and line is a Unicode string? Should we emit a warning?

I patched locally PyUnicode_RichCompare() to emit a warning. Hum, there are *many* warnings in argparse, http.client, and many other modules. I don't think that it's a good idea. It looks common to use a string for a sentinel (ex: state = "UNKNOWN") and then store an int (ex: state = 0). So comparison need to check the type (ex: isinstance(state, str) and state == "UNKNOWN") which is verbose and annoying.

So no, we should not emit a warning :-)