Use pyupgrade to upgrade the code to use Python3 conventions (#138)

The pyupgrade project is available at
https://github.com/asottile/pyupgrade and can be installed through pip.

The pyupgrade tool automatically upgrades syntax for newer versions of
the language. As pyparsing is now Python 3 only, can apply some cleanups
and simplifications. Ran the tool using the following command:

    $ find . -name \*.py -exec pyupgrade --py3-plus {} \;

For now, pyparsing.py was skipped while it is refactored to a package.

1 files changed, 2 insertions, 2 deletions

diff --git a/examples/shapes.py b/examples/shapes.py
index 55af19a..b0fe979 100644
--- a/examples/shapes.py
+++ b/examples/shapes.py
@@ -7,7 +7,7 @@
 #
 
 # define class hierarchy of Shape classes, with polymorphic area method
-class Shape(object):
+class Shape:
     def __init__(self, tokens):
         self.__dict__.update(tokens.asDict())
 
@@ -15,7 +15,7 @@ class Shape(object):
         raise NotImplemented()
 
     def __str__(self):
-        return "<{0}>: {1}".format(self.__class__.__name__, vars(self))
+        return "<{}>: {}".format(self.__class__.__name__, vars(self))
 
 class Square(Shape):
     def area(self):