Add binary strings python interview problem

This video goes over a solution to the following Daily Byte problem in python:

Given two binary strings (strings containing only 1s and 0s) return their sum (also as a binary string).
Note: neither binary string will contain leading 0s unless the string itself is 0

Ex: Given the following binary strings...

"100" + "1", return "101"
"11" + "1", return "100"
"1" + "0", return "1"