I was recomended by former Bloomberg employee. They contacted me in a week or two and scheduled Skype video call. Two guys, one is native speaker, the other has russian accent. We started with a technical problem (group strings from vector by anagrams). Then, because of my mistake in sort(vector) they asked how all STL methods work. I fixed my mistake and we talked about different iterator types. Question about fuctors you can pass to STL functions, then about metric and its properties. After that we moved to machine learning.