Correct index item

espinoza · web-flow · commit 54245db1ecaa · 2019-12-28T22:56:26.000-03:00
diff --git a/book/book.tex b/book/book.tex
@@ -8472,7 +8472,7 @@ \section{Exercises}
 
 \begin{exercise}
 \index{append method}
-\index{method append}
+\index{method!append}
 \index{list!concatenation}
 \index{concatenation!list}
 
