gnu: Add python-flake8-continuation.

* gnu/packages/python-xyz.scm (python-flake8-continuation): New variable.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/python-xyz.scm

@@ -8735,6 +8735,34 @@ design problems in your program.  It contains warnings that don't belong
 in pyflakes and pycodestyle.")
     (license license:expat)))
 
+(define-public python-flake8-continuation
+  (package
+    (name "python-flake8-continuation")
+    (version "1.0.5")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (pypi-uri "flake8-continuation" version))
+       (sha256
+        (base32
+         "0dzaw8jr7yhlabxhrblnrizxx17xa9ngjnbr1kidg5lapq6b9q1y"))))
+    (build-system python-build-system)
+    (propagated-inputs
+     `(("python-flake8" ,python-flake8)
+       ("python-pycodestyle" ,python-pycodestyle)
+       ("python-six" ,python-six)))
+    (home-page "https://github.com/planetlabs/flake8-continuation")
+    (synopsis "Flake8 Line Continuation Plugin")
+    (description "A Flake8 plugin that checks for the line continuation
+style to be in the preferred method according to PEP-8, specifically:
+@quotation
+The preferred way of wrapping long lines is by using Python's implied
+line continuation inside parentheses, brackets and braces.  Long lines
+can be broken over multiple lines by wrapping expressions in parentheses.
+These should be used in preference to using a backslash for line continuation.
+@end quotation")
+    (license license:asl2.0)))
+
 (define-public python-flake8-implicit-str-concat
   (package
     (name "python-flake8-implicit-str-concat")