update
diff --git a/input/tree_structure.xml b/input/tree_structure.xml
new file mode 100644
index 0000000..ec65299
--- /dev/null
+++ b/input/tree_structure.xml
@@ -0,0 +1,3 @@
+<?xml version="1.0" ?>
+<teiCorpus>
+</teiCorpus>