I am going through 101 now can Still sign up for 102?
You can definitely sign up for the 102 before you have completed the 101. You just have to complete the 101 before attending the 102. When you sign up for the 102, the system will automatically check to see if you have taken the 101, if you have not completed it, you can be sent a notification. This is sent to everyone and you can ignore it if you know that you are taking it. It's a reminder to to let people know about the prerequisite.