# File lib/iq_rdf/document.rb, line 18
    def initialize(default_namespace_uri_prefix = nil, *args)
      options = args.last.is_a?(::Hash) ? args.pop : {}
      raise ArgumentError, "If given, parameter :lang has to be a Symbol" unless options[:lang].nil? || options[:lang].is_a?(Symbol)

      self.namespaces(:default => default_namespace_uri_prefix) if default_namespace_uri_prefix
      self.namespaces(:rdf => "http://www.w3.org/1999/02/22-rdf-syntax-ns#")

      @document_language = options[:lang]

      @nodes = []
    end