ReadonlyMap<string, string> type ReadonlyMap<string, string>
import {LANG_BY_EXTENSION} from '@fuzdev/zzz/path_lang.js'; File extensions (lowercase, without the dot) and the fuz_code language each
is highlighted as — a primary id registered on fuz_code's
syntax_styler_global. JavaScript is highlighted by the TypeScript lexer
(it registers js as an alias); JSX and TSX are left out, since that lexer
doesn't read their markup.