bug fix: number of args for difference constructor

ngsrinivas · ngsrinivas · commit 39875757331c · 2014-01-18T12:56:26.000-08:00
diff --git a/pyretic/core/language.py b/pyretic/core/language.py
@@ -181,7 +181,7 @@ def __sub__(self, pol):
         :rtype: Difference
         """
         if isinstance(pol,Filter):
-            return difference([self, pol])
+            return difference(self, pol)
         else:
             raise TypeError
 
