def collapse_parent node=:current_index
      node = row_to_node if node == :current_index
      parent = node.parent
      return if parent.nil?
      goto_parent node
      collapse_node parent
    end
def collapse_parent node=:current_index
      node = row_to_node if node == :current_index
      parent = node.parent
      return if parent.nil?
      goto_parent node
      collapse_node parent
    end
collapse parent
 can use multiplier.
 # we need to move up also