list vs tuple, multithreading in python, web socket vs tcp socket, implement calc of math expresion, return unique in list, count repetition in list. meta class, descriptor, named tuple; get2sum with o(n) and o(n) space; get2sum with o(nlogn) without extra memory; implement queue with two stacks; parse protobuf to dict; class method vs static vs instanse; struct vs class in c++; implement template of array; iterator; gnerator; implement binary tree; print it in order; object managment in python;