gistfile1.txt

class Node
  attr_accessor :children
  def initialize
    @children = []
  end
  def to_s
    "Node with children #{children.to_s}"
  end
end

a = Node.new
a.children << Node.new
a.children[0].children << a
puts a
# Output: Node with children [Node with children [Node with children [...]]]
# (Literal ellipsis were included in output, I didn't add them.)