traverse_bottom_up

# File actiontext/lib/action_text/plain_text_conversion.rb, line 141
          def traverse_bottom_up(node, &block)
            call_stack, processing_stack = [ node ], []

            until call_stack.empty?
              node = call_stack.pop
              processing_stack.push(node)
              call_stack.concat node.children
            end

            processing_stack.reverse_each(&block)
          end