They're reference designs for a reason.

A Select Committee of Parliament appointed to inquire into the release of 323 containers from the Port of Colombo without mandatory physical inspection has decided to meet weekly and complete its ...

or located under the following github pages github.io. Additionally in combination with the technical datasheet of microchip PCF8574-Datasheet. PCF8574_I2C::PCF8574 pcf{0x20, &Wire}; void setup() { ...