python cosmetics

book.tex

@@ -16437,7 +16437,7 @@ class Tagged:
   \code{Vector}, and \code{Procedure}.}
 %
 \python{The tags are \code{'int'}, \code{'bool'}, \code{'none'},
-  \code{'tuple'}, and \code{'function'}}
+  \code{'tuple'}, and \code{'function'}.}
 %
 Tags are closely related to types
 but don't always capture all the information that a type does.