diff --git a/pymath/generic.py b/pymath/generic.py
index c911b27..b83d809 100644
--- a/pymath/generic.py
+++ b/pymath/generic.py
@@ -8,7 +8,6 @@ class Stack(object):
     """Docstring for Stack """
 
     def __init__(self):
-        """@todo: to be defined1 """
         self.items = []
 
     def pushFromList(self, list):
@@ -21,7 +20,6 @@ class Stack(object):
 
     def isEmpty(self):
         """ Says if the stack is empty
-        :returns: @todo
 
         """
         return self.items == []
@@ -29,9 +27,6 @@ class Stack(object):
     def push(self,  item):
         """Push an item in the stack
 
-        :param item: @todo
-        :returns: @todo
-
         """
         self.items.append(item)
 
diff --git a/pymath/operator.py b/pymath/operator.py
index 6ffbb49..b643cad 100644
--- a/pymath/operator.py
+++ b/pymath/operator.py
@@ -116,7 +116,6 @@ class Operator(str):
         :*args: Operands for this operation
         :returns: list with the operator surrounded by operands
 
-        # TODO: order doctest  |lun. nov. 24 07:17:29 CET 2014
         >>> op.mul.__p2i__(1,2)
         [1, '*', 2]
         >>> f = save_mainOp([2, op.add, 3],op.add)
@@ -131,9 +130,7 @@ class Operator(str):
         >>> op.sub1.__p2i__(f)
         ['-', '(', 2, '+', 3, ')']
         """
-        # TODO: Attention à gestion des fractions qui se comportent chelou avec les parenthèses |dim. nov.  9 09:21:52 CET 2014
         if self.arity == 1:
-            # TODO: Marche juste avec -, il faudra voir quand il y aura d'autres operateurs unitaires |dim. nov.  9 09:24:53 CET 2014
             op1 = self.l_parenthesis(args[0])
             ans = flatten_list([self, op1])
 
@@ -165,7 +162,6 @@ class Operator(str):
 
     def r_parenthesis(self, op, str_join=False):
         """ Add parenthesis for rigth operand if necessary """
-        # TODO: /!\ Parenthèses pour -2abc et l'opérateur * |lun. mars  9 19:02:32 CET 2015
         try:
             if op.mainOp.priority < self.priority:
                 op = flatten_list(["(", op, ")"])
diff --git a/pymath/render.py b/pymath/render.py
index 67e70d8..4c58f07 100644
--- a/pymath/render.py
+++ b/pymath/render.py
@@ -77,11 +77,12 @@ if __name__ == '__main__':
     from itertools import permutations
     from pymath import Polynom
     from pymath import Expression 
+    from pymath import Fraction
     coefs_p = [[(i-2),(j-2)] for i,j in permutations(range(5),2)] 
     coefs_q = [[2*(i-2),2*(j-2)] for i,j in permutations(range(5),2)] 
     l_p = [Polynom(i) for i in coefs_p]
-    l_q = [Polynom(i) for i in coefs_q]
-    operations = [Expression([l_p[i],l_q[j],op.pw]) for i,j in permutations(range(len(coefs_p)),2)]
+    l_q = [Fraction(i,j) for i,j in coefs_q if j!=0]
+    operations = [Expression([l_p[i],l_q[j],op.mul]) for i,j in permutations(range(len(l_q)),2)]
     for i in operations:
         print(i)