Write up a draft cell list computation.
Write up a draft cell list computation.

Co-authored-by: Sam Schoenholz <5507631b18c4b8f8deae8c809e6e37d5af66b8db@google.com>

google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang