Add checks for `not x in y` and `not x is None`

[alex]

These would error on code like:

not x in y and not x is None

and suggest

x not in y and x is not None

This can be based on this code from OpenStack: https://github.com/openstack-dev/hacking/blob/master/hacking/core.py#L808

[markmc]

Here's a stable version of that URL : https://github.com/openstack-dev/hacking/blob/cd31f92/hacking/core.py#L808

:)

[chrismedrela]

I've created a fix that bases on the OpenStack solution. I've introduced W605 and W606 error numbers.

[myint]

@chrismedrela, should it be in the statement (E71) category? It seems fairly similar to E711 and E712.

[sigmavirus24]

I agree with @myint. Also I wouldn't call that older syntax "deprecated" @chrismedrela. It is just not good form or style.

[florentx]

Thank you @chrismedrela for this feature request, it's a benefit for code readability.

[jogo]

While I am happy to see others using our hacking checks, I am confused why this is in the pep8 project since this rule isn't in pep8 itself: http://legacy.python.org/dev/peps/pep-0008/

So why does this belong in the pep8 project if its not in the pep8 standard itself?

[florentx]

you're right.

I've reported it upstream: http://bugs.python.org/issue21540