Good modernization advice from Terry J. Reedy:

Don't use list, dict, file, and such as variable names.

pep-0290.txt

@@ -180,6 +180,21 @@ sufficient for most uses.
 Locating: ``grep types *.py | grep import``
 
 
+Avoid Variable Names that Clash with the ``__builtins__`` Module
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+In Python 2.2, new built-in types were added for ``dict`` and ``file``.
+Scripts should avoid assigning variable names that mask those types.
+The same advice also applies to existing builtins like ``list``.
+
+Pattern::
+
+    file = open('myfile.txt') --> f = open('myfile.txt')
+    dict = obj.__dict__ --> d = obj.__dict__
+
+Locating:  ``grep 'file ' *.py``
+
+
 Python 2.1 or Later
 -------------------