Get rid of most flake8 errors

setup.cfg

@@ -8,5 +8,8 @@ ignore =
   E722,
   # don't know why this was ever even an option, 1+1 should be possible.
   E226,
-  # line break before binary operator
+  # Sometimes `type() is` makes sense and is better than isinstance. Code
+  # review is there to find the times when it doesn't make sense.
+  E721,
+  # Line break before binary operator
   W503,