    # File lib/action_controller/routing/optimisations.rb, line 67
            def guard_conditions
              number_of_arguments = route.required_segment_keys.size
              # if they're using foo_url(:id=>2) it's one
              # argument, but we don't want to generate /foos/id2
              if number_of_arguments == 1
                ["args.size == 1", "!args.first.is_a?(Hash)"]
              else
                ["args.size == #{number_of_arguments}"]
              end
            end