How about this? Is it too long?
@Matthew Barnett, I'm animalize on your repository.

.. seealso::

    Third-party module `regex <https://pypi.python.org/pypi/regex>`_,

    is a substitute for re module, it offers some mainstream features 
    which re module lacks (Atomic grouping, Possessive quantifiers,
    Variable-length lookbehind, Recursive matching). It also has further
    Unicode support, some advanced grammars appears in other regular
    expression engines, and many facilitations.