fixes #1002 (#1042)

Author: martin-henz

xml/chapter2/section3/subsection3.xml

@@ -1482,6 +1482,7 @@ tree_to_list_2(union_set_as_tree(
 	</JAVASCRIPT>
       </SNIPPET>
       <SNIPPET>
+	<NAME>intersection_set_as_tree_solution</NAME>
 	<REQUIRES>intersection_set_ordered</REQUIRES>
 	<REQUIRES>list_to_tree</REQUIRES>
 	<REQUIRES>tree_to_list_2</REQUIRES>
@@ -1639,6 +1640,7 @@ lookup(3, list(make_record(2, "Venus"),
     <LABEL NAME="ex:set-lookup-binary-tree"/>
     <SOLUTION>
       <SNIPPET>
+	<NAME>ex_set_lookup_binary_tree</NAME>
 	<REQUIRES>make_tree_function</REQUIRES>
 	<REQUIRES>record</REQUIRES>
 	<EXAMPLE>lookup_example2</EXAMPLE>