side-by-side diff review on typical screen resolutions. Long lines also make it harder
to present code neatly in documentation or talk slides.
-If you're using Flake8, you can bump `max-line-length` to 88 and forget about it.
-Alternatively, use [Bugbear](https://github.com/PyCQA/flake8-bugbear)'s B950 warning
-instead of E501 and keep the max line length at 80 which you are probably already using.
-You'd do it like this:
+If you're using Flake8, you can bump `max-line-length` to 88 and mostly forget about it.
+However, it's better if you use [Bugbear](https://github.com/PyCQA/flake8-bugbear)'s
+B950 warning instead of E501, and bump the max line length to 88 (or the `--line-length`
+you used for black), which will align more with black's _"try to respect
+`--line-length`, but don't become crazy if you can't"_. You'd do it like this:
```ini
[flake8]
-max-line-length = 80
+max-line-length = 88
...
select = C,E,F,W,B,B950
-ignore = E203, E501, W503
+extend-ignore = E203, E501
```
-You'll find _Black_'s own .flake8 config file is configured like this. Explanation of
-why W503 and E203 are disabled can be found further in this documentation. And if you're
-curious about the reasoning behind B950,
+Explanation of why E203 is disabled can be found further in this documentation. And if
+you're curious about the reasoning behind B950,
[Bugbear's documentation](https://github.com/PyCQA/flake8-bugbear#opinionated-warnings)
explains it. The tl;dr is "it's like highway speed limits, we won't bother you if you
overdo it by a few km/h".
_Black_ will add trailing commas to expressions that are split by comma where each
element is on its own line. This includes function signatures.
-Unnecessary trailing commas are removed if an expression fits in one line. This makes it
-1% more likely that your line won't exceed the allotted line length limit. Moreover, in
-this scenario, if you added another argument to your call, you'd probably fit it in the
-same line anyway. That doesn't make diffs any larger.
-
-One exception to removing trailing commas is tuple expressions with just one element. In
-this case _Black_ won't touch the single trailing comma as this would unexpectedly
-change the underlying data type. Note that this is also the case when commas are used
-while indexing. This is a tuple in disguise: `numpy_array[3, ]`.
-
One exception to adding trailing commas is function signatures containing `*`, `*args`,
or `**kwargs`. In this case a trailing comma is only safe to use on Python 3.6. _Black_
will detect if your file is already 3.6+ only and use trailing commas in this situation.
comma in this situation and _Black_ didn't recognize it was safe to do so, put it there
manually and _Black_ will keep it.
+A pre-existing trailing comma informs _Black_ to always explode contents of the current
+bracket pair into one item per line. Read more about this in the
+[Pragmatism](#pragmatism) section below.
+
### Strings
_Black_ prefers double quotes (`"` and `"""`) over single quotes (`'` and `'''`). It
[PEP 8](https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator)
style guide, which emphasizes that this approach improves readability.
-This behaviour may raise `W503 line break before binary operator` warnings in style
-guide enforcement tools like Flake8. Since `W503` is not PEP 8 compliant, you should
-tell Flake8 to ignore these warnings.
-
### Slices
PEP 8
How do you make it stop? Just delete that trailing comma and _Black_ will collapse your
collection into one line if it fits.
+If you must, you can recover the behaviour of early versions of Black with the option
+`--skip-magic-trailing-comma` / `-C`.
+
### r"strings" and R"strings"
_Black_ normalizes string quotes as well as string prefixes, making them lowercase. One
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