[UVM basics] connect of UVM_ Phase execution sequence

And build_phase And main_phase similar , connect_phase It's also UVM A built-in phase, It's in build_phase Execute as soon as the execution is complete . But with the build_phase The difference is , Its execution order is not from root to leaf , But from leaves to roots —— Execute first driver and monitor Of connect_phase, Re execution agent Of connect_phase, Finally, execute env Of connect_phase.