formated correctly for pep8

Author: markbasham

src/demo/foo.py

@@ -8,11 +8,14 @@
 def add(a, b):
     return a+b
 
+
 def sub(a, b):
     return a-b
 
+
 def mul(a, b):
     return a*b
 
+
 def div(a, b):
     return a/b