tweak python rules

Author: Peter Mounce

.flake8

@@ -1,5 +1,7 @@
 # https://flake8.pycqa.org/en/latest/user/configuration.html#configuration-locations
+# +
+# https://github.com/psf/black/blob/master/docs/the_black_code_style.md#line-length
 [flake8]
-ignore =
-    # don't care about line length.
-    E501
+# black wraps at 88
+max-line-length = 90
+extend-ignore = E203

.pre-commit-config.yaml

@@ -76,3 +76,5 @@ repos:
     rev: 20.8b1
     hooks:
       - id: black
+        args:
+          - --skip-string-normalization