This might be deeper than you are looking for, but this is the theory it's based on, and even has diagrams. :) https://arxiv.org/abs/1311.3903 https://arxiv.or

This might be deeper than you are looking for, but this is the theory it's based on, and even has diagrams. :) https://arxiv.org/abs/1311.3903 https://arxiv.org/abs/1311.3903