Check if PCF8574 is online

[epiller]

Hello Renzo,

Thanks for this great library! It is the only one that worked with a custom I2C port on ESP32.

I'm running a critical button over the PCF8574 that should never false trigger, so now I'm writing the logic in case PCF8574 isn't online or fails for whatever reason since, as you know, the pin state can flip if you disconnect the PCF8574. I'd like to avoid that.

Thanks to your begin() returning a boolean value, this is possible during initialization, but how can I check if the PCF8574 is online and working before every read? Do you have a recommendation?

Thanks!