design decisions
top down or bottom up index generation? bottom up feels better for some reason
if were top down, config file format start simple (TOML), relax later if needed (YAML) https://martin-ueding.de/posts/json-vs-yaml-vs-toml/ https://jhall.io/posts/best-config-file-formats/ https://stackoverflow.com/questions/65283208/toml-vs-yaml-vs-strictyaml