pyupgrade is a tool to automatically upgrade syntax for newer versions
of the Python language.

The project has been Python 3 only since
35544e2fc6eed0ce4a27ec7285aac71ff0ddc473, allowing for several cleanups:

- Remove unnecessary "-*- coding: utf-8 -*-" cookie. Python 3 reads all
  source files as utf-8 by default.

- Replace IOError/EnvironmentError with OSError. Python 3 unified these
  exceptions. The old names are aliases only.

- Use the Python 3 shorter super() syntax.

- Remove "utf8" argument form encode/decode. In Python 3, this value is
  the default.

- Remove "r" from open() calls. In Python 3, this value is the default.

- Remove u prefix from Unicode strings. In Python 3, all strings are
  Unicode.

- Replace io.open() with builtin open(). In Python 3, these functions
  are functionally equivalent.

Co-authored-by: Matthäus G. Chajdas <Anteru@users.noreply.github.com>

fixes #1223

* Fix an issue raised in the review -- don't raise None no matter what.
* Remove a few variables to make the control flow easier to understand

This is slightly different from the code posted inside the issue:
* Use finally to close the registry key no matter what
* Don't use break, but return directly on the first hit

* Remove Python 2 compatibility

* remove 2/3 shims in pygments.util
* update setup.py metadata

* Remove unneeded object inheritance.

* Remove unneeded future imports.

Run the pyupgrade tool across the project to use modern language
features.

- Use set literals
- Use dict comprehension
- Remove unnecessary numeric indexes in format string
- Remove unnecessary extra parentheses