deepmap
Maps with multiple keys per value
Supports the following Map methods:
clear
delete
has
get
set
All other Map methods & properties, including well-known symbols and coercion logic, are not catered for at present.
Signature for all methods is the same as for Map, except that in place of a key, it instead accepts an array of keys.
map method key value? )
...DeepMaps instead provide:
map method ...keys value? )
Ergo:
const sums = sums sums // false sums // false sums // true sums // 3 sums // true sums // false