docs: adds ExitStack alternative to future_style.md (#3247)

Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

docs/conf.py

@@ -55,7 +55,7 @@ def make_pypi_svg(version: str) -> None:
 # -- General configuration ---------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-needs_sphinx = "3.0"
+needs_sphinx = "4.4"
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom

docs/the_black_code_style/future_style.md

@@ -34,6 +34,19 @@ with \
 Although when the target version is Python 3.9 or higher, _Black_ will use parentheses
 instead since they're allowed in Python 3.9 and higher.
 
+An alternative to consider if the backslashes in the above formatting are undesirable is
+to use {external:py:obj}`contextlib.ExitStack` to combine context managers in the
+following way:
+
+```python
+with contextlib.ExitStack() as exit_stack:
+    cm1 = exit_stack.enter_context(make_context_manager(1))
+    cm2 = exit_stack.enter_context(make_context_manager(2))
+    cm3 = exit_stack.enter_context(make_context_manager(3))
+    cm4 = exit_stack.enter_context(make_context_manager(4))
+    ...
+```
+
 ## Preview style
 
 Experimental, potentially disruptive style changes are gathered under the `--preview`