Recommended way to add ordinal suffix for the day of month?

I cannot find the ordinal suffix for the month in the Timex.Format.DateTime.Formatter module. Similar to what PHP has for their datetime:
English ordinal suffix for the day of the month, 2 characters | st, nd, rd or th.
http://php.net/manual/en/function.date.php

Is a custom formatter recommended to add the suffix?

Start with the Timex.Format.DateTime.Formatter module named in the issue and review how existing date formatting options are implemented. Compare the requested English day-of-month suffix behavior with the referenced PHP behavior; done should mean the project has a decided, documented approach or an implemented formatter with matching coverage.

Written by the indexing model from the issue text.