def to_nt
      time_serialization('nt') do
        if @criteria
          @criteria.serialize(:return_graph => @return_graph, :accept_header => Tripod.ntriples_header_str)
        elsif @sparql_query_str && @resource_class
          # run the query as a describe.
          @resource_class._raw_describe_select_results(@sparql_query_str, :accept_header => Tripod.ntriples_header_str)
        else
          # for n-triples we can just concatenate them
          nt = ""
          resources.each do |resource|
            nt += resource.to_nt
          end
          nt
        end
      end
    end
def to_nt
      time_serialization('nt') do
        if @criteria
          @criteria.serialize(:return_graph => @return_graph, :accept_header => Tripod.ntriples_header_str)
        elsif @sparql_query_str && @resource_class
          # run the query as a describe.
          @resource_class._raw_describe_select_results(@sparql_query_str, :accept_header => Tripod.ntriples_header_str)
        else
          # for n-triples we can just concatenate them
          nt = ""
          resources.each do |resource|
            nt += resource.to_nt
          end
          nt
        end
      end
    end
for n-triples we can just concatenate them