There is only one round interview, which is directly talking to the lab chair. Very friendly chat. There are two main topics. First is about personal experience, like name, background, interests. Then the professor asks some questions about skills related to the research subjects. For my case, if your previous work is sufficient, there will not be coding qustions.

Brief one on one interview that was very relaxed. I emailed beforehand asking about positions and to set up a time to meet. We went over interests and different types of research.