Commit 2020-12-12 04:38 f51fe7b6

chore(data/fin): Improve docstrings, rename coe_sub_nat, add nat_add_zero (#5290) These are cherry-picked from the tuple PR, #4406. coe_sub_nat was previously named sub_nat_coe, but this didn't match coe_nat_add and coe_add_nat.