fix join's type

diff --git a/topics/week7_introducing_monads.mdwn b/topics/week7_introducing_monads.mdwn
index 191f35d..61012d5 100644 (file)
--- a/topics/week7_introducing_monads.mdwn
+++ b/topics/week7_introducing_monads.mdwn
@@ -105,7 +105,7 @@ Here are the types of our crucial functions, together with our pronunciation, an
 
 <code>=&lt;&lt; or mdnib (flip mbind) (<u>Q</u>) -> (Q -> <u>R</u>) -> (<u>R</u>)</code>
 
-<code>join: <span class="double">P</span> -> <u>P</u></code> 
+<code>join: <span class="box2">P</span> -> <u>P</u></code> 
 
 
 The menagerie isn't quite as bewildering as you might suppose. Many of these will