Add Tag support to the post type.
Add Post Format support to the post type.
No recursion. Remove $max_id and $since_id args, we'll handle it internally.
Add and use a prefix_with_hashtag function, to make sure the tag is appropriately prefixed.
Indent appropriately to match previous line.
Add create_posts function  that takes an array, and calls new create_post function directly.
If it returns 100 statuses, search and create posts again, as it's maxed out.