# File kwartz.rb, line 1014
        def traverse_with_parent(depth=0, parent=nil, &block)
            yield(self, depth, parent)
            [@left, @right, @condition].each do |node|
                if node && node.is_a?(Node)
                    node.traverse_with_parent(depth+1, self, &block)
                end
            end
        end