is-thirteen

Provides chainable methods like `is(13).thirteen()` and `is(12.8).roughly.thirteen()`, making code readable and playful, as demonstrated in the README examples.

Allows performing calculations with `plus`, `minus`, `times`, and `divideby` before checking equality, enabling checks like `is(14).minus(1).thirteen()` which returns true.

Includes `roughly.thirteen()` for approximate checks and `within().of.thirteen()` for range-based validation, offering nuanced checks beyond basic equality.

Embraces humor with a WTFPL license and creative documentation, turning a trivial task into an enjoyable coding exercise.