Convert raise statements in Tools/.
diff --git a/Tools/unicode/mkstringprep.py b/Tools/unicode/mkstringprep.py
index b910d69..83a5d8f 100644
--- a/Tools/unicode/mkstringprep.py
+++ b/Tools/unicode/mkstringprep.py
@@ -1,7 +1,7 @@
 import re, unicodedata, sys
 
 if sys.maxunicode == 65535:
-    raise RuntimeError, "need UCS-4 Python"
+    raise RuntimeError("need UCS-4 Python")
 
 def gen_category(cats):
     for i in range(0, 0x110000):