Locker Studio Session Length between multiple events

Question

I'm a seasoned user of Amplitude, but recently I started using Locker Studio. Here's my situation:

• I have a event_timestamp, event_type and session_id for each event I log;
• For each session_id I want to:
  • take the event_timestamp when event_type = 1 (Session Start);
  • take the event_timestamp when event_type = 2 (Session Start);
  • (ignore any other event_type's value);
  • compute the diff (Session Length)
• (Know how) Then with these, I want to calculate the average and show it on a score card.

With Amplitude, this was pretty easy. Can anybody help me to achieve this goal on LockerStudio?

Thank you!