# File lib/ruote/util/tree.rb, line 50
  def Ruote.tree_to_s (tree, expid='0')

    d = expid.split('_').size - 1
    s = "#{' ' * d * 2}#{expid}  #{tree[0]} #{tree[1].inspect}\n"
    tree[2].each_with_index { |t, i| s << tree_to_s(t, "#{expid}_#{i}") }
    s
  end