NB: this is a post to remember things, not really expecting to give someone enough information to be able to hack the Cylc Scheduler (though you can and would have fun!).
configure method is responsible for configuring the Suite Server Program. Which
means it will interact with the configuration singletons to retrieve the necessary
configuration for the program.
It also interacts with other objects that store state, and also creates basic data structures and objects required for a suite program (e.g. Queues).
This is also where the contact file is created, as well as the HTTP server.