How to Configure an ESP Mesh Network using Arduino IDE –

Hi I'm having a problem in line

 taskSendMessage.setInterval( random( TASK_SECOND * 1, TASK_SECOND * 5 ));

Error message: 'taskSendMessage was not declared in this scope.'

I've tried various libraries and added dependancies after using the links from article but to no effect.

I have had another painless mesh working but cannot solve this.  Can you help please.

Bob