I approached by cold mailing and instantly got heard back, The process took a total of 2 weeks with 3 rounds in it.
round 1) Basic background understanding and Technical assessment , comprised of basic python questions ( Very Easy)
round 2) Home Assignment - Comprised of coding Ability , Domain Knowledge and mathematics. ( Advice to do it yourself)
round 3) Thorough Q&A from the submitted assignment, focused on reasoning behind the codes and logic, though if you have done it by yourself would be a piece of cake.