diff --git a/voka/metrics/chisq.py b/voka/metrics/chisq.py
index 552b6f7..1cd5e99 100644
--- a/voka/metrics/chisq.py
+++ b/voka/metrics/chisq.py
@@ -1,52 +1,59 @@
+'''
+Module contains two functions objects that calculate
+a ChiSq for both cases where two sets are assumed
+to have the same normalization and not.
+'''
 
-class NormChiSq(object):
-    r"""Compare sequences v1, v2 with a Chi^2 test.
+class NormChiSq:
+    r"""Compare sequences vector1, vector2 with a Chi^2 test.
         Assumes they have the same binning.
         Output:
         chisq : float
             A Chi^2 sum over all bins.
     """
-    
-    def __call__(self, v1, v2):
 
-        assert(len(v1) == len(v2))
-        
+    def __call__(self, vector1, vector2):
+        '''
+        Calculate the ChiSq
+        '''
+
+        assert len(vector1) == len(vector2)
+
         # calculate the \chi^2 test statistic
         terms = [(u - v)**2/(u + v) \
-                 for u,v in zip(v1, v2)\
+                 for u, v in zip(vector1, vector2)\
                  if u > 0 and v > 0]
-        T = sum(terms)
-        return T
-    
-    
-class ShapeChiSq(object):
-    r"""Compare sequences v1, v2 with a Chi^2 test after normalizing them.
-    Assumes they have the same binning.
+        result = sum(terms)
+        return result
+
+class ShapeChiSq:
+    r"""Compare sequences vector1, vector2 with a Chi^2 test after
+    normalizing them.
     Output:
         chisq : float
-            A Chi^2 sum over all bins.            
+            A Chi^2 sum over all bins.
     """
 
-    def __call__(self, v1, v2):
-        
-        assert(len(v1) == len(v2))
-        
-        n1 = sum(v1)
-        n2 = sum(v2)
+    def __call__(self, vector1, vector2):
+        '''
+        Calculate the ChiSq
+        '''
+        assert len(vector1) == len(vector2)
+
+        sum1 = sum(vector1)
+        sum2 = sum(vector2)
         try:
-            n1sq = n1**2
-            n2sq = n2**2
-            terms = [(u/n1 - v/n2)**2/(u/n1sq + v/n2sq) \
-                     for u,v in zip(v1, v2) \
-                     if u > 0 and v > 0 ]             
+            n1sq = sum1**2
+            n2sq = sum2**2
+            terms = [(u/sum1 - v/sum2)**2/(u/n1sq + v/n2sq) \
+                     for u, v in zip(vector1, vector2) \
+                     if u > 0 and v > 0]
         except ZeroDivisionError:
-            s = float(n1)/n2
-            ssq = s**2
-            terms = [(u/s - v)**2/(u/ssq + v) \
-                     for u,v in zip(v1, v2) \
-                     if u > 0 and v > 0 ]
-            
-        T = sum(terms)
-        return T
-    
-    
+            ratio = float(sum1)/sum2
+            ssq = ratio**2
+            terms = [(u/ratio - v)**2/(u/ssq + v) \
+                     for u, v in zip(vector1, vector2) \
+                     if u > 0 and v > 0]
+
+        result = sum(terms)
+        return result