modernize some modules' code by using with statement around open()
diff --git a/Lib/symtable.py b/Lib/symtable.py
index 39c1a80..c0e32df 100644
--- a/Lib/symtable.py
+++ b/Lib/symtable.py
@@ -235,7 +235,8 @@
 
 if __name__ == "__main__":
     import os, sys
-    src = open(sys.argv[0]).read()
+    with open(sys.argv[0]) as f:
+        src = f.read()
     mod = symtable(src, os.path.split(sys.argv[0])[1], "exec")
     for ident in mod.get_identifiers():
         info = mod.lookup(ident)