class Link
    #attr_accessor :source, :target

    def initialize(arg)
      @args = arg
      if @args[:source] == nil
        raise Exception.new("source cant be nil")
      end

      if @args[:target] == nil
        raise Exception.new("target cant be nil")
      end

      if not @args[:source].is_a? Node
        raise Exception.new("source must be of type Node")
      end

      if not @args[:target].is_a? Node
        raise Exception.new("target must be of type Node")
      end

      @args[:weight] ||= 1

      @args[:source].neighbours << @args[:target]
      @args[:target].neighbours << @args[:source]
    end

    def method_missing(name, *args)
      super unless args.empty?
      @args[name]
    end
  end