Raise statement normalization in Lib/.
diff --git a/Lib/pty.py b/Lib/pty.py
index 5d588e4..4873827 100644
--- a/Lib/pty.py
+++ b/Lib/pty.py
@@ -57,7 +57,7 @@
         try:
             tty_name, master_fd = sgi._getpty(os.O_RDWR, 0o666, 0)
         except IOError as msg:
-            raise os.error, msg
+            raise os.error(msg)
         return master_fd, tty_name
     for x in 'pqrstuvwxyzPQRST':
         for y in '0123456789abcdef':
@@ -67,7 +67,7 @@
             except os.error:
                 continue
             return (fd, '/dev/tty' + x + y)
-    raise os.error, 'out of pty devices'
+    raise os.error('out of pty devices')
 
 def slave_open(tty_name):
     """slave_open(tty_name) -> slave_fd