Lib/argparse.py uses `is` for string comparison,

`
221:            if self.heading is not SUPPRESS and self.heading is not None:
247:        if text is not SUPPRESS and text is not None:
251:        if usage is not SUPPRESS:
256:        if action.help is not SUPPRESS:
290:                        if part and part is not SUPPRESS])
679:            if action.default is not SUPPRESS:
1130:        if self.dest is not SUPPRESS:
1766:            if action.dest is not SUPPRESS:
1768:                    if action.default is not SUPPRESS:
1851:            if argument_values is not SUPPRESS:
2026:                             if action.help is not SUPPRESS]
`

where `SUPPRESS = '==SUPPRESS=='`. Unless I'm missing something this can produce false negatives if the variable that we compare against is a slice from another string. Using equality is probably safer in any case.

Detected with LGTM.com analysis.

argparse.SUPPRESS is an opaque value to be used by argparse clients. It could be anything, it just happens to be a string. So the code doesn't compare strings but checks whether a supplied object *is* the opaque value. I do not see any problem with this code, though one way to avoid LGTM diagnostics would be to use a non-string opaque value instead.

I concur with Alexey. This is a correct use of the 'is' operator.

Thanks, Alexey and Serhiy! Looking at the code more closely I would agree. I guess changing the value of the suppress object to something else to avoid the warning, has a potential of breaking code that relies on the current functionality and is not worth it...