const [member, num] = await parseArgs(args, [
  {
    type: 'member',
    me: msg.member,
    guild: msg.channel.guild,
  },
  {
    type: 'integer',
    lowerBound: 1,
  },
]);

registerArgumentType('foo', (args, options) => {
  // do something with args to get your type
  // options is one of the objects passed to parseArgs, you can pull custom options from there
  // remember to modify the args array so other argument resolvers don't try to parse the same text
  return args.shift().length > options.customThing;
// (async resolvers are also supported)
});
const [val] = await parseArgs(['somethingVeryLong'], [
  {
    type: 'foo',
    customThing: 3,
  }
]);
val //> true (since "somethingVeryLong" has more than 3 characters)