* Refactored the is operator for simplicity and efficiency.
* Improve `is` filter documentation.
* Update is.js
* extracted `subops.length` to `num_of_subops`
* renamed `subop` to `operator` for clarity/differentiation from `subops`
* refactored to avoid using a `Set` object.
* Update is.js
* Modify the is operator to allow multiple types to be specified.
* Fixed indentation.
* Fixed indentation.
* Rewritten to maintain input order when multiple filters provided.
* Updated documentation.
* Update is.tid