+/* type predicates. */
+#include "global-context.hh"
+#include "input.hh"
+#include "item.hh"
+#include "music.hh"
+#include "music-function.hh"
+#include "paper-score.hh"
+#include "performance.hh"
+#include "protected-scm.hh"
+#include "spanner.hh"
+#include "stream-event.hh"
+#include "unpure-pure-container.hh"
+
+static Protected_scm doc_hash_table;