# File lib/rd/tree.rb, line 92
    def Tree.new_from_rdo(*rdos) # rdos: IOs
      tree = Tree.new("", [], nil)
      tree_content = []
      rdos.each do |i|
        subtree = Marshal.load(i)
        tree_content.concat(subtree.root.blocks)
      end
      tree.root = DocumentElement.new(tree_content)
      tree
    end