create_user = (fn email <str>, name <option(str)>) <map> {
	{
		email = email
		username = (either_or name email)
	}
}

(assert_equal
	{
		email = "bob@example.com"
		username = "bob"
	},
	(create_user "bob@example.com" some("bob"))
)

(assert_equal
	{
		email = "sue@example.com"
		username = "sue@example.com"
	},
	(create_user "sue@example.com" none)
)