How to use the @creditkarma/thrift-server-core.MessageType function in @creditkarma/thrift-server-core

)
                                const metadata: Core.IThriftMessage = input.readMessageBegin()
                                const fieldName: string = metadata.fieldName
                                const requestId: number = metadata.requestId

                                const output: Core.TProtocol = new Protocol(
                                    new Transport(),
                                )
                                const exception: Core.TApplicationException = new Core.TApplicationException(
                                    Core.TApplicationExceptionType.INTERNAL_ERROR,
                                    response.message as string, // If we're dealing with an error this is an Error not a Response
                                )

                                output.writeMessageBegin(
                                    fieldName,
                                    Core.MessageType.EXCEPTION,
                                    requestId,
                                )
                                Core.TApplicationExceptionCodec.encode(
                                    exception,
                                    output,
                                )
                                output.writeMessageEnd()

                                return reply.response(output.flush()).code(500)
                            } catch (err) {
                                logger(
                                    ['error', 'ThriftServerHapi'],
                                    `Unable to build TApplicationException for response error: ${err.message}`,
                                )
                                return reply.continue
                            }

(
                        req: http.IncomingMessage,
                        res: http.ServerResponse,
                    ): void => {
                        if (count < 1) {
                            count += 1
                            const upgradeResponse: TTwitter.IUpgradeReply = {}
                            const writer: thrift.TTransport = new thrift.BufferedTransport()
                            const output: thrift.TProtocol = new thrift.BinaryProtocol(
                                writer,
                            )
                            output.writeMessageBegin(
                                'add',
                                thrift.MessageType.CALL,
                                1,
                            )
                            TTwitter.UpgradeReplyCodec.encode(
                                upgradeResponse,
                                output,
                            )
                            output.writeMessageEnd()
                            res.writeHead(200)
                            res.end(writer.flush())
                        } else {
                            const responseHeader: TTwitter.IResponseHeader = {}
                            const writer: thrift.TTransport = new thrift.BufferedTransport()
                            const output: thrift.TProtocol = new thrift.BinaryProtocol(
                                writer,
                            )
                            output.writeMessageBegin(

socket.addListener('data', (chunk: Buffer) => {
                        const writer: thrift.TTransport = new thrift.BufferedTransport()
                        const output: thrift.TProtocol = new thrift.BinaryProtocol(
                            writer,
                        )
                        output.writeMessageBegin(
                            'add',
                            thrift.MessageType.CALL,
                            1,
                        )
                        const result: Calculator.IAdd__Result = {
                            success: 102,
                        }
                        Calculator.Add__ResultCodec.encode(result, output)
                        output.writeMessageEnd()
                        const data: Buffer = writer.flush()

                        socket.write(frameCodec.encode(data))
                    })
                })

handler(
                        request: IThriftRequest,
                        next: NextFunction,
                    ): Promise {
                        const writer: thrift.TTransport = new thrift.BufferedTransport()
                        const output: thrift.TProtocol = new thrift.BinaryProtocol(
                            writer,
                        )
                        output.writeMessageBegin(
                            'addWithContext',
                            thrift.MessageType.CALL,
                            20,
                        )
                        const args: Calculator.AddWithContext__Args = new Calculator.AddWithContext__Args(
                            { num1: 20, num2: 60 },
                        )
                        args.write(output)
                        output.writeMessageEnd()
                        return next(writer.flush())
                    },
                },