import { DrainOption } from "https://deno.land/x/sane_fmt@0.15.1/x/args.ts";
Declare an option that drains all arguments after the flag
CLI example: --opt abc def ghi
→ ['abc', 'def', 'ghi']
type
<Name extends string, Value>(name: Name, descriptor: DrainOptionDescriptor<Value>) => FlagType<Name, Value[]>