use enumerate() when we need an iterator's item AND index

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32723 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/XMLMatrix.py

@@ -494,12 +494,10 @@ class XMLMatrix(Folder):
       if not self.index.has_key(cell_id):
         return None
 
-      i = 0
       base_item = self.index[base_id]
-      for my_id in kw:
+      for i, my_id in enumerate(kw):
         if base_item[i].has_key(my_id):
           cell_id += '_%s' % base_item[i][my_id]
-          i += 1
         else:
           raise KeyError, 'Invalid key: %s' % str(kw)