PEP 8 updates on hanging continuation lines, based on discussion from

python-ideas (contributed by Steven Klass).

pep-0008.txt

@@ -57,28 +57,38 @@ Code lay-out
     For really old code that you don't want to mess up, you can continue to
     use 8-space tabs.
 
-    Continuation lines should align wrapped elements either vertically using 
-    Python's implicit line joining inside parentheses, brackets and braces,
-    or using a hanging indent of double your code indention, in which case 
-    there should be no argument on the first line. For example:
+    Continuation lines should align wrapped elements either vertically using
+    Python's implicit line joining inside parentheses, brackets and braces, or
+    using a hanging indent.  When using a hanging indent the following
+    considerations should be applied; there should be no arguments on the
+    first line and further indentation should be used to clearly distinguish
+    itself as a continuation line.
 
     Yes:  # Aligned with opening delimiter
           foo = long_function_name(var_one, var_two,
                                    var_three, var_four)
 
-          # Double code indention for hanging indent; nothing on first line
-          foo = long_function_name(
+          # More indentation included to distinguish this from the rest.
+          def long_function_name(
                   var_one, var_two, var_three,
-                  var_four)
+                  var_four):
+              print(var_one)
 
-    No:   # Stuff on first line forbidden
+    No:   # Arguments on first line forbidden when not using vertical alignment
           foo = long_function_name(var_one, var_two,
               var_three, var_four)
 
-          # 2-space hanging indent forbidden
+          # Further indentation required as indentation is not distinguishable
+          def long_function_name(
+              var_one, var_two, var_three,
+              var_four):
+              print(var_one)
+
+    Optional:
+          # Extra indentation is not necessary.
           foo = long_function_name(
-            var_one, var_two, var_three,
-            var_four) 
+            var_one, var_two,
+            var_three, var_four)
 
   Tabs or Spaces?