The new `Intl.ListFormat` in JS gets so much right.
1. Serial/Oxford/Harvard comma is used for American English (en-US)
2. `en` behavior is that of American English, not British English
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/ListFormat
I dare someone to change the MDN docs list to `["my parents", "Ayn Rand", "God"]`.
