-### Command line options
-
-*Black* doesn't provide many options. You can list them by running
-`black --help`:
-
-```text
-black [OPTIONS] [SRC]...
-
-Options:
- -c, --code TEXT Format the code passed in as a string.
- -l, --line-length INTEGER How many characters per line to allow.
- [default: 88]
- -t, --target-version [py27|py33|py34|py35|py36|py37|py38]
- Python versions that should be supported by
- Black's output. [default: per-file auto-
- detection]
- --py36 Allow using Python 3.6-only syntax on all
- input files. This will put trailing commas
- in function signatures and calls also after
- *args and **kwargs. Deprecated; use
- --target-version instead. [default: per-file
- auto-detection]
- --pyi Format all input files like typing stubs
- regardless of file extension (useful when
- piping source on standard input).
- -S, --skip-string-normalization
- Don't normalize string quotes or prefixes.
- --check Don't write the files back, just return the
- status. Return code 0 means nothing would
- change. Return code 1 means some files
- would be reformatted. Return code 123 means
- there was an internal error.
- --diff Don't write the files back, just output a
- diff for each file on stdout.
- --fast / --safe If --fast given, skip temporary sanity
- checks. [default: --safe]
- --include TEXT A regular expression that matches files and
- directories that should be included on
- recursive searches. An empty value means
- all files are included regardless of the
- name. Use forward slashes for directories
- on all platforms (Windows, too). Exclusions
- are calculated first, inclusions later.
- [default: \.pyi?$]
- --exclude TEXT A regular expression that matches files and
- directories that should be excluded on
- recursive searches. An empty value means no
- paths are excluded. Use forward slashes for
- directories on all platforms (Windows, too).
- Exclusions are calculated first, inclusions
- later. [default: /(\.eggs|\.git|\.hg|\.mypy
- _cache|\.nox|\.tox|\.venv|_build|buck-
- out|build|dist)/]
- -q, --quiet Don't emit non-error messages to stderr.
- Errors are still emitted, silence those with
- 2>/dev/null.
- -v, --verbose Also emit messages to stderr about files
- that were not changed or were ignored due to
- --exclude=.
- --version Show the version and exit.
- --config PATH Read configuration from PATH.
- -h, --help Show this message and exit.
-```
-
-*Black* is a well-behaved Unix-style command-line tool:
-* it does nothing if no sources are passed to it;
-* it will read from standard input and write to standard output if `-`
- is used as the filename;
-* it only outputs messages to users on standard error;
-* exits with code 0 unless an internal error occurred (or `--check` was
- used).
-
-
-### NOTE: This is a beta product
-
-*Black* is already [successfully used](#used-by) by many projects, small and big.
-It also sports a decent test suite. However, it is still very new.
-Things will probably be wonky for a while. This is made explicit by the
-"Beta" trove classifier, as well as by the "b" in the version number.
-What this means for you is that **until the formatter becomes stable,
-you should expect some formatting to change in the future**. That being
-said, no drastic stylistic changes are planned, mostly responses to bug
-reports.
-
-Also, as a temporary safety measure, *Black* will check that the
-reformatted code still produces a valid AST that is equivalent to the
-original. This slows it down. If you're feeling confident, use
-``--fast``.
-
-
-## The *Black* code style
-
-*Black* reformats entire files in place. It is not configurable. It
-doesn't take previous formatting into account. It doesn't reformat
-blocks that start with `# fmt: off` and end with `# fmt: on`. `# fmt: on/off`
-have to be on the same level of indentation. It also
-recognizes [YAPF](https://github.com/google/yapf)'s block comments to
-the same effect, as a courtesy for straddling code.
-
-
-### How *Black* wraps lines
-
-*Black* ignores previous formatting and applies uniform horizontal
-and vertical whitespace to your code. The rules for horizontal
-whitespace can be summarized as: do whatever makes `pycodestyle` happy.
-The coding style used by *Black* can be viewed as a strict subset of
-PEP 8.
-
-As for vertical whitespace, *Black* tries to render one full expression
-or simple statement per line. If this fits the allotted line length,
-great.
-```py3
-# in:
-
-l = [1,
- 2,
- 3,
-]
-
-# out:
-
-l = [1, 2, 3]
-```
-
-If not, *Black* will look at the contents of the first outer matching
-brackets and put that in a separate indented line.
-```py3
-# in:
-
-ImportantClass.important_method(exc, limit, lookup_lines, capture_locals, extra_argument)
-
-# out:
-
-ImportantClass.important_method(
- exc, limit, lookup_lines, capture_locals, extra_argument
-)
-```
-
-If that still doesn't fit the bill, it will decompose the internal
-expression further using the same rule, indenting matching brackets
-every time. If the contents of the matching brackets pair are
-comma-separated (like an argument list, or a dict literal, and so on)
-then *Black* will first try to keep them on the same line with the
-matching brackets. If that doesn't work, it will put all of them in
-separate lines.
-```py3
-# in:
-
-def very_important_function(template: str, *variables, file: os.PathLike, engine: str, header: bool = True, debug: bool = False):
- """Applies `variables` to the `template` and writes to `file`."""
- with open(file, 'w') as f:
- ...
-
-# out:
-
-def very_important_function(
- template: str,
- *variables,
- file: os.PathLike,
- engine: str,
- header: bool = True,
- debug: bool = False,
-):
- """Applies `variables` to the `template` and writes to `file`."""
- with open(file, "w") as f:
- ...
-```
-
-You might have noticed that closing brackets are always dedented and
-that a trailing comma is always added. Such formatting produces smaller
-diffs; when you add or remove an element, it's always just one line.
-Also, having the closing bracket dedented provides a clear delimiter
-between two distinct sections of the code that otherwise share the same
-indentation level (like the arguments list and the docstring in the
-example above).
-
-If a data structure literal (tuple, list, set, dict) or a line of "from"
-imports cannot fit in the allotted length, it's always split into one
-element per line. This minimizes diffs as well as enables readers of
-code to find which commit introduced a particular entry. This also
-makes *Black* compatible with [isort](https://pypi.org/p/isort/) with
-the following configuration.
-
-<details>
-<summary>A compatible `.isort.cfg`</summary>
-
-```
-[settings]
-multi_line_output=3
-include_trailing_comma=True
-force_grid_wrap=0
-use_parentheses=True
-line_length=88
-```
-
-The equivalent command line is:
-```
-$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --use-parentheses --line-width=88 [ file.py ]
-```
-</details>
-
-### Line length
-
-You probably noticed the peculiar default line length. *Black* defaults
-to 88 characters per line, which happens to be 10% over 80. This number
-was found to produce significantly shorter files than sticking with 80
-(the most popular), or even 79 (used by the standard library). In
-general, [90-ish seems like the wise choice](https://youtu.be/wf-BqAjZb8M?t=260).
-
-If you're paid by the line of code you write, you can pass
-`--line-length` with a lower number. *Black* will try to respect that.
-However, sometimes it won't be able to without breaking other rules. In
-those rare cases, auto-formatted code will exceed your allotted limit.
-
-You can also increase it, but remember that people with sight disabilities
-find it harder to work with line lengths exceeding 100 characters.
-It also adversely affects 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:
-```ini
-[flake8]
-max-line-length = 80
-...
-select = C,E,F,W,B,B950
-ignore = E501
-```
-
-You'll find *Black*'s own .flake8 config file is configured like this.
-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".
-
-
-### Empty lines
-
-*Black* avoids spurious vertical whitespace. This is in the spirit of
-PEP 8 which says that in-function vertical whitespace should only be
-used sparingly.
-
-*Black* will allow single empty lines inside functions, and single and
-double empty lines on module level left by the original editors, except
-when they're within parenthesized expressions. Since such expressions
-are always reformatted to fit minimal space, this whitespace is lost.
-
-It will also insert proper spacing before and after function definitions.
-It's one line before and after inner functions and two lines before and
-after module-level functions and classes. *Black* will not put empty
-lines between function/class definitions and standalone comments that
-immediately precede the given function/class.
-
-*Black* will enforce single empty lines between a class-level docstring
-and the first following field or method. This conforms to
-[PEP 257](https://www.python.org/dev/peps/pep-0257/#multi-line-docstrings).
-
-*Black* won't insert empty lines after function docstrings unless that
-empty line is required due to an inner function starting immediately
-after.
-
-
-### Trailing commas
-
-*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. If you
-wonder how it knows, it looks for f-strings and existing use of trailing
-commas in function signatures that have stars in them. In other words,
-if you'd like a trailing comma in this situation and *Black* didn't
-recognize it was safe to do so, put it there manually and *Black* will
-keep it.
-
-
-### Strings
-
-*Black* prefers double quotes (`"` and `"""`) over single quotes (`'`
-and `'''`). It will replace the latter with the former as long as it
-does not result in more backslash escapes than before.
-
-*Black* also standardizes string prefixes, making them always lowercase.
-On top of that, if your code is already Python 3.6+ only or it's using
-the `unicode_literals` future import, *Black* will remove `u` from the
-string prefix as it is meaningless in those scenarios.
-
-The main reason to standardize on a single form of quotes is aesthetics.
-Having one kind of quotes everywhere reduces reader distraction.
-It will also enable a future version of *Black* to merge consecutive
-string literals that ended up on the same line (see
-[#26](https://github.com/python/black/issues/26) for details).
-
-Why settle on double quotes? They anticipate apostrophes in English
-text. They match the docstring standard described in [PEP 257](https://www.python.org/dev/peps/pep-0257/#what-is-a-docstring).
-An empty string in double quotes (`""`) is impossible to confuse with
-a one double-quote regardless of fonts and syntax highlighting used.
-On top of this, double quotes for strings are consistent with C which
-Python interacts a lot with.
-
-On certain keyboard layouts like US English, typing single quotes is
-a bit easier than double quotes. The latter requires use of the Shift
-key. My recommendation here is to keep using whatever is faster to type
-and let *Black* handle the transformation.
-
-If you are adopting *Black* in a large project with pre-existing string
-conventions (like the popular ["single quotes for data, double quotes for
-human-readable strings"](https://stackoverflow.com/a/56190)), you can
-pass `--skip-string-normalization` on the command line. This is meant as
-an adoption helper, avoid using this for new projects.
-
-### Numeric literals
-
-*Black* standardizes most numeric literals to use lowercase letters for the
-syntactic parts and uppercase letters for the digits themselves: `0xAB`
-instead of `0XAB` and `1e10` instead of `1E10`. Python 2 long literals are
-styled as `2L` instead of `2l` to avoid confusion between `l` and `1`.
-
-
-### Line breaks & binary operators
-
-*Black* will break a line before a binary operator when splitting a block
-of code over multiple lines. This is so that *Black* is compliant with the
-recent changes in the [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 [recommends](https://www.python.org/dev/peps/pep-0008/#whitespace-in-expressions-and-statements)
-to treat ``:`` in slices as a binary operator with the lowest priority, and to
-leave an equal amount of space on either side, except if a parameter is omitted
-(e.g. ``ham[1 + 1 :]``). It also states that for extended slices, both ``:``
-operators have to have the same amount of spacing, except if a parameter is
-omitted (``ham[1 + 1 ::]``). *Black* enforces these rules consistently.
-
-This behaviour may raise ``E203 whitespace before ':'`` warnings in style guide
-enforcement tools like Flake8. Since ``E203`` is not PEP 8 compliant, you should
-tell Flake8 to ignore these warnings.
-
-
-### Parentheses
-
-Some parentheses are optional in the Python grammar. Any expression can
-be wrapped in a pair of parentheses to form an atom. There are a few
-interesting cases:
-
-- `if (...):`
-- `while (...):`
-- `for (...) in (...):`
-- `assert (...), (...)`
-- `from X import (...)`
-- assignments like:
- - `target = (...)`
- - `target: type = (...)`
- - `some, *un, packing = (...)`
- - `augmented += (...)`
-
-In those cases, parentheses are removed when the entire statement fits
-in one line, or if the inner expression doesn't have any delimiters to
-further split on. If there is only a single delimiter and the expression
-starts or ends with a bracket, the parenthesis can also be successfully
-omitted since the existing bracket pair will organize the expression
-neatly anyway. Otherwise, the parentheses are added.
-
-Please note that *Black* does not add or remove any additional nested
-parentheses that you might want to have for clarity or further
-code organization. For example those parentheses are not going to be
-removed:
-```py3
-return not (this or that)
-decision = (maybe.this() and values > 0) or (maybe.that() and values < 0)
-```
-
-
-### Call chains
-
-Some popular APIs, like ORMs, use call chaining. This API style is known
-as a [fluent interface](https://en.wikipedia.org/wiki/Fluent_interface).
-*Black* formats those by treating dots that follow a call or an indexing
-operation like a very low priority delimiter. It's easier to show the
-behavior than to explain it. Look at the example:
-```py3
-def example(session):
- result = (
- session.query(models.Customer.id)
- .filter(
- models.Customer.account_id == account_id,
- models.Customer.email == email_address,
- )
- .order_by(models.Customer.id.asc())
- .all()
- )
-```
-
-
-### Typing stub files
-
-PEP 484 describes the syntax for type hints in Python. One of the
-use cases for typing is providing type annotations for modules which
-cannot contain them directly (they might be written in C, or they might
-be third-party, or their implementation may be overly dynamic, and so on).
-
-To solve this, [stub files with the `.pyi` file
-extension](https://www.python.org/dev/peps/pep-0484/#stub-files) can be
-used to describe typing information for an external module. Those stub
-files omit the implementation of classes and functions they
-describe, instead they only contain the structure of the file (listing
-globals, functions, and classes with their members). The recommended
-code style for those files is more terse than PEP 8:
-
-* prefer `...` on the same line as the class/function signature;
-* avoid vertical whitespace between consecutive module-level functions,
- names, or methods and fields within a single class;
-* use a single blank line between top-level class definitions, or none
- if the classes are very small.
-
-*Black* enforces the above rules. There are additional guidelines for
-formatting `.pyi` file that are not enforced yet but might be in
-a future version of the formatter:
-
-* all function bodies should be empty (contain `...` instead of the body);
-* do not use docstrings;
-* prefer `...` over `pass`;
-* for arguments with a default, use `...` instead of the actual default;
-* avoid using string literals in type annotations, stub files support
- forward references natively (like Python 3.7 code with `from __future__
- import annotations`);
-* use variable annotations instead of type comments, even for stubs that
- target older versions of Python;
-* for arguments that default to `None`, use `Optional[]` explicitly;
-* use `float` instead of `Union[int, float]`.
-
-
-## pyproject.toml
-
-*Black* is able to read project-specific default values for its
-command line options from a `pyproject.toml` file. This is
-especially useful for specifying custom `--include` and `--exclude`
-patterns for your project.
-
-**Pro-tip**: If you're asking yourself "Do I need to configure anything?"
-the answer is "No". *Black* is all about sensible defaults.
-
-
-### What on Earth is a `pyproject.toml` file?
-
-[PEP 518](https://www.python.org/dev/peps/pep-0518/) defines
-`pyproject.toml` as a configuration file to store build system
-requirements for Python projects. With the help of tools
-like [Poetry](https://poetry.eustace.io/) or
-[Flit](https://flit.readthedocs.io/en/latest/) it can fully replace the
-need for `setup.py` and `setup.cfg` files.
-
-
-### Where *Black* looks for the file
-
-By default *Black* looks for `pyproject.toml` starting from the common
-base directory of all files and directories passed on the command line.
-If it's not there, it looks in parent directories. It stops looking
-when it finds the file, or a `.git` directory, or a `.hg` directory,
-or the root of the file system, whichever comes first.
-
-If you're formatting standard input, *Black* will look for configuration
-starting from the current working directory.
-
-You can also explicitly specify the path to a particular file that you
-want with `--config`. In this situation *Black* will not look for any
-other file.
-
-If you're running with `--verbose`, you will see a blue message if
-a file was found and used.
-
-Please note `blackd` will not use `pyproject.toml` configuration.
-
-
-### Configuration format
-
-As the file extension suggests, `pyproject.toml` is a [TOML](https://github.com/toml-lang/toml) file. It contains separate
-sections for different tools. *Black* is using the `[tool.black]`
-section. The option keys are the same as long names of options on
-the command line.
-
-Note that you have to use single-quoted strings in TOML for regular
-expressions. It's the equivalent of r-strings in Python. Multiline
-strings are treated as verbose regular expressions by Black. Use `[ ]`
-to denote a significant space character.
-
-<details>
-<summary>Example `pyproject.toml`</summary>
-
-```toml
-[tool.black]
-line-length = 88
-target-version = ['py37']
-include = '\.pyi?$'
-exclude = '''
-
-(
- /(
- \.eggs # exclude a few common directories in the
- | \.git # root of the project
- | \.hg
- | \.mypy_cache
- | \.tox
- | \.venv
- | _build
- | buck-out
- | build
- | dist
- )/
- | foo.py # also separately exclude a file named foo.py in
- # the root of the project
-)
-'''
-```
-
-</details>
-
-### Lookup hierarchy
-
-Command-line options have defaults that you can see in `--help`.
-A `pyproject.toml` can override those defaults. Finally, options
-provided by the user on the command line override both.
-
-*Black* will only ever use one `pyproject.toml` file during an entire
-run. It doesn't look for multiple files, and doesn't compose
-configuration from different levels of the file hierarchy.
-
-
-## Editor integration
-
-### Emacs
-
-Use [proofit404/blacken](https://github.com/proofit404/blacken) or
-[Elpy](https://github.com/jorgenschaefer/elpy).
-
-
-### PyCharm/IntelliJ IDEA
-
-1. Install `black`.
-
-```console
-$ pip install black
-```
-
-2. Locate your `black` installation folder.
-
- On macOS / Linux / BSD:
-
-```console
-$ which black
-/usr/local/bin/black # possible location
-```
-
- On Windows:
-
-```console
-$ where black
-%LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe # possible location
-```
-
-3. Open External tools in PyCharm/IntelliJ IDEA
-
- On macOS:
-
-```PyCharm -> Preferences -> Tools -> External Tools```
-
- On Windows / Linux / BSD:
-
-```File -> Settings -> Tools -> External Tools```
-
-4. Click the + icon to add a new external tool with the following values:
- - Name: Black
- - Description: Black is the uncompromising Python code formatter.
- - Program: <install_location_from_step_2>
- - Arguments: `"$FilePath$"`
-
-5. Format the currently opened file by selecting `Tools -> External Tools -> black`.
- - Alternatively, you can set a keyboard shortcut by navigating to `Preferences or Settings -> Keymap -> External Tools -> External Tools - Black`.
-
-6. Optionally, run *Black* on every file save:
-
- 1. Make sure you have the [File Watcher](https://plugins.jetbrains.com/plugin/7177-file-watchers) plugin installed.
- 2. Go to `Preferences or Settings -> Tools -> File Watchers` and click `+` to add a new watcher:
- - Name: Black
- - File type: Python
- - Scope: Project Files
- - Program: <install_location_from_step_2>
- - Arguments: `$FilePath$`
- - Output paths to refresh: `$FilePath$`
- - Working directory: `$ProjectFileDir$`
- - Uncheck "Auto-save edited files to trigger the watcher"
-
-
-
-### Wing IDE
-
-Wing supports black via the OS Commands tool, as explained in the Wing documentation on [pep8 formatting](https://wingware.com/doc/edit/pep8). The detailed procedure is:
-
-1. Install `black`.
-
-```console
-$ pip install black
-```
-
-2. Make sure it runs from the command line, e.g.
projects / etc / vim.git / blobdiff