client = mqtt.Client(client_id="myclientid",clean_session=False)

client.on_connect = on_connect
client.on_message = on_message

client.connect("localhost",1883,60)
client.loop_forever()
```

Execute this example python program to watch for MQTT events on the console.

```py
python mqtt.py
```

        // Setting onConnect to null should work
        request.onConnect(null);

        assertNotNull(request);
    }

    @Test
    public void testMultipleOnConnectCalls() {
        CurlRequest request = new CurlRequest(Method.GET, "https://example.com");

        // Multiple onConnect calls should work (last one wins)
        request.onConnect((req, conn) -> conn.setConnectTimeout(1000));

// Op is operation type messages.
type Op uint8

// HandlerID is the ID for the handler of a specific type.
type HandlerID uint8

const (
	// OpConnect is a connect request.
	OpConnect Op = iota + 1

	// OpConnectResponse is a response to a connect request.
	OpConnectResponse

	// OpPing is a ping request.
	// If a mux id is specified that mux is pinged.

            mockHolder[0] = mock;
            return mock;
        });
        req.timeout(3000, 5000);
        // onConnect runs AFTER timeout, so it can override
        req.onConnect((r, conn) -> {
            conn.setReadTimeout(9999);
            onConnectReadTimeout.set(conn.getReadTimeout());
        });

        // ## Act ##

package grid

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[OpConnect-1]
	_ = x[OpConnectResponse-2]
	_ = x[OpPing-3]
	_ = x[OpPong-4]
	_ = x[OpConnectMux-5]
	_ = x[OpMuxConnectError-6]
	_ = x[OpDisconnectClientMux-7]
	_ = x[OpDisconnectServerMux-8]
	_ = x[OpMuxClientMsg-9]

      }

      OverrideParam.ConnectTimeout -> {
        client =
          client
            .newBuilder()
            .socketFactory(
              DelayingSocketFactory(onConnect = { timeout ->
                if (timeout == 10) {
                  throw IOException()
                }
              }),
            ).build()

            } else if (entry.getValue().length == 1) {
                curlRequest.param(entry.getKey(), entry.getValue()[0]);
            }
        });
        try (final CurlResponse curlResponse = curlRequest.onConnect((req, con) -> {
            con.setDoOutput(true);
            if (httpMethod != Method.GET && request.getContentLength() > 2) {

        }

        final ObjectMapper mapper = new ObjectMapper();
        final AtomicBoolean resetJobs = new AtomicBoolean(false);
        try (CurlResponse response = ComponentUtil.getCurlHelper().post("/_bulk").onConnect((req, con) -> {
            con.setDoOutput(true);
            try (final BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(tempFile)));

    /**
     * Sets the connection builder for customizing the connection.
     *
     * @param connectionBuilder the connection builder
     * @return this CurlRequest instance
     */
    public CurlRequest onConnect(final BiConsumer<CurlRequest, HttpURLConnection> connectionBuilder) {
        this.connectionBuilder = connectionBuilder;
        return this;
    }

    /**
     * Adds a request parameter.
     *

	}

	var message message
	_, _, err = message.parse(msg)
	if err != nil {
		writeErr(fmt.Errorf("error parsing grid connect: %w", err))
		return
	}
	if message.Op != OpConnect {
		writeErr(fmt.Errorf("unexpected connect op: %v", message.Op))
		return
	}
	var cReq connectReq
	_, err = cReq.UnmarshalMsg(message.Payload)
	if err != nil {