问将代码从JS转换为C#。我不明白这个函数是干什么的

EN

    const yandexRequests = (function() {
      var protoRequest = new protobuf.Type("VideoTranslationRequest").add(new protobuf.Field("url", 3, "string")).add(new protobuf.Field("deviceId", 4, "string")).add(new protobuf.Field("unknown0", 5, "int32")).add(new protobuf.Field("unknown1", 6, "fixed64")).add(new protobuf.Field("unknown2", 7, "int32")).add(new protobuf.Field("language", 8, "string")).add(new protobuf.Field("unknown3", 9, "int32")).add(new protobuf.Field("unknown4", 10, "int32"));
      var protoResponse = new protobuf.Type("VideoTranslationResponse").add(new protobuf.Field("url", 1, "string")).add(new protobuf.Field("status", 4, "int32"));
      new protobuf.Root().define("yandex").add(protoRequest).add(protoResponse);
      return {
          encodeRequest: function(url, deviceId, unknown1) {
              return protoRequest.encode({url: url, deviceId: deviceId, unknown0: 1, unknown1: unknown1, unknown2: 1, language: "en", unknown3: 0, unknown4: 0}).finish();
          },
          decodeResponse: function(response) {
              return protoResponse.decode(new Uint8Array(response));
          }
      };
  })();