I just completed "Operation Order" - Day 18 - Advent of Code 2020
https://adventofcode.com/2020/day/18 #AdventOfCode

https://github.com/coderbyheart/adventofcode/tree/6b9ebe2053f664c95169654a62bbe3cc4a398c5f/day18

For step 2 I re-implemented my parser to tokenize the expression, but I ended up
putting all additions in parenthesis before calculating it.