Cambridge Mobile Telematics interview question

Python internals and optimization for latency, garbage collection etc 1st screening hackerrank - Python based app/ code that needed fixing - react and sql based qs 2nd - System design and work based questions - Scalable systems, concurrency, db level optimizations sharding partitioning 3rd - Similar work based questions on past experience 4th US based tech round - Huge python code asked to find issues review them answered all of them including optimizations i believe