Clarify why we define disco.  Suggested by Andrew Dalke.
diff --git a/Lib/dis.py b/Lib/dis.py
index c997880..a03784c 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -83,7 +83,7 @@
 				print '(' + cmp_op[oparg] + ')',
 		print
 
-disco = disassemble
+disco = disassemble			# XXX For backwards compatibility
 
 def findlabels(code):
 	"""Detect all offsets in a byte code which are jump targets.