# File lib/iq_rdf/node.rb, line 29
    def <<(node)
      raise ArgumentError, "#{node.inspect} is no IqRdf::Node or a IqRdf::Literal or a IqRdf::Collection" unless node.is_a?(IqRdf::Node) || node.is_a?(IqRdf::Literal) || node.is_a?(IqRdf::Collection)
      @nodes << node
    end