Patch# 1258 by Christian Heimes: kill basestring.
I like this because it makes the code shorter! :-)
diff --git a/Modules/_csv.c b/Modules/_csv.c
index 0df85b6..2ebbf38 100644
--- a/Modules/_csv.c
+++ b/Modules/_csv.c
@@ -62,7 +62,7 @@
 /* end 2.2 compatibility macros */
 
 #define IS_BASESTRING(o) \
-	PyObject_TypeCheck(o, &PyBaseString_Type)
+	PyUnicode_Check(o)
 
 static PyObject *error_obj;	/* CSV exception */
 static PyObject *dialects;      /* Dialect registry */