1. `class A(object)` can be written as `class A:`
2. replace `dict([…])` and `set([…])` with `{…}`
3. use f-strings or compact `.format`
4. use `yield from` instead of `yield` in a `for` loop
5. import `mock` from `unittest`
6. expect `OSError` instead of `IOError` or `select` error
7. use Python3 defaults for file reading or `super()`
8. remove redundant parenthesis (keep those in tuples though)
9. shorten set intersection instead of creating lists
10. backslashes in strings do not have to be escaped if prepended with `r`
* added black to develop guide
* no need for pep8radius.
* changelog.
* Add pre-commit checkbox.
* Add pre-commit to dev reqs.
* Add pyproject.toml for black.
* Pre-commit config.
* Add black to travis and dev reqs.
* Install and run black in travis.
* Remove black from dev reqs.
* Lower black target version.
* Re-format with black.