code: def _insert_tree(cursor, tree, parent_id=None, index=0, is_collated=False):
      
      if isinstance(tree, dict):
          if tree['id'] == 'subcol':
              document_id = None
              title = tree['title']
          else:
              cursor.execute("""\
              SELECT module_ident, name
              FROM modules
              WHERE ident_hash(uuid,major_version,minor_version) = %s
              """, (tree['id'],))
              try:
                  document_id, document_title = cursor.fetchone()
              except TypeError:  # NoneType
                  raise ValueError("Missing published document for '{}'."
                                   .format(tree['id']))
              if tree.get('title', None):
                  title = tree['title']
              else:
                  title = document_title
          # TODO We haven't settled on a flag (name or value)
          #      to pin the node to a specific version.
          is_latest = True
          cursor.execute(TREE_NODE_INSERT,
                         dict(document_id=document_id, parent_id=parent_id,
                              title=title, child_order=index,
                              is_latest=is_latest, is_collated=is_collated))
          node_id = cursor.fetchone()[0]
          if 'contents' in tree:
              _insert_tree(cursor, tree['contents'], parent_id=node_id,
                           is_collated=is_collated)
      elif isinstance(tree, list):
          for tree_node in tree:
              _insert_tree(cursor, tree_node, parent_id=parent_id,
                           index=tree.index(tree_node), is_collated=is_collated)
docs: Inserts a binder tree into the archive.