# File lib/fog/network/openstack/requests/add_router_interface.rb, line 5
        def add_router_interface(router_id, subnet_id_or_options)
          if subnet_id_or_options.kind_of? String
            data = {
              'subnet_id' => subnet_id_or_options,
            }
          elsif subnet_id_or_options.kind_of? Hash
            data = subnet_id_or_options
          else
            raise ArgumentError, 'Please pass a subnet id or hash {subnet_id:xxx,port_id:xxx}'
          end

          request(
            :body    => Fog::JSON.encode(data),
            :expects => [200],
            :method  => 'PUT',
            :path    => "routers/#{router_id}/add_router_interface"
          )
        end