add #occurs_free

diff --git a/exercises/assignment5.mdwn b/exercises/assignment5.mdwn
index a74da85..dabc1a0 100644 (file)
--- a/exercises/assignment5.mdwn
+++ b/exercises/assignment5.mdwn
@@ -252,6 +252,7 @@ Again, we've left some gaps. (The use of `type` for the first line in Haskell an
 
 15. Choose one of these languages and fill in the gaps to complete the definition.
 
+<a id="occurs_free"></a>
 16. Write a function `occurs_free` that has the following type:
 
         occurs_free : identifier -> lambda_term -> bool