--- a/python/ir/builder.py	Fri Apr 19 12:42:21 2013 +0200
+++ b/python/ir/builder.py	Fri Apr 19 19:22:52 2013 +0200
@@ -9,14 +9,16 @@
             yield a
             a = a + 1
       self.nums = NumGen()
-   def gen(self):
-      return '{0}{1}'.format(self.prefix, self.nums.__next__())
+   def gen(self, prefix=None):
+      if not prefix:
+         prefix = self.prefix
+      return '{0}{1}'.format(prefix, self.nums.__next__())
 
 class ValueGenerator(NameGenerator):
    def __init__(self):
       super().__init__('t')
-   def gen(self):
-      v = Value(super().gen())
+   def gen(self, prefix=None):
+      v = Value(super().gen(prefix))
       return v
 
 class BBGenerator(NameGenerator):