That is known as railroad diagrams and provided by sites such as regulex[0] (which I used for js cover) and debuggex [1]. I've also mentioned it in acknowledgem

That is known as railroad diagrams and provided by sites such as regulex[0] (which I used for js cover) and debuggex [1]. I've also mentioned it in acknowledgements within the book. [0] https://jex.im/regulex https://jex.im/regulex [1] https://www.debuggex.com/ https://www.debuggex.com/