Squashed 'homotopy/torus-paper/drl-common/' content from commit 8b77474

git-subtree-dir: homotopy/torus-paper/drl-common
git-subtree-split: 8b774748e8ab328fadd5fc375fa85c8dd0cb9db0
Merge commit '451955761d642901e1de6ed9c7eeb659b86f9ac4' as 'homotopy/torus-paper/drl-common'
draft intro