I would recommend using one of the existing modules for this job.

It isn't a large amount of work to duplicate the functionality, but the time it takes to document your new module and the time it takes to put together a comprehensive test suite can be substantial.

Someone else has already done this work, so it would be better to use their existing code and test suite. They might have thought of rare cases that you would have missed. And if you know of a case they don't test for, I'm sure the maintainer would appreciate a well written test case for it.