+@register.simple_tag
+def book_tree_texml(book_list, books_by_parent, depth=1):
+ return "".join("""
+ <cmd name='hspace'><parm>%(depth)dem</parm></cmd>%(title)s
+ <spec cat='align' /><cmd name="note"><parm>%(audiences)s</parm></cmd>
+ <spec cat='align' /><cmd name="note"><parm>%(audiobook)s</parm></cmd>
+ <ctrl ch='\\' />
+ %(children)s
+ """ % {
+ "depth": depth,
+ "title": book.title,
+ "audiences": ", ".join(book.audiences_pl()),
+ "audiobook": "audiobook" if book.has_media('mp3') else "",
+ "children": book_tree_texml(books_by_parent.get(book.id, ()), books_by_parent, depth + 1)
+ } for book in book_list)
+