* The named tuple class should begin with a capital letter and be fully self-documenting: "RequestRate".

* The creation of the named tuple class should be done only once, not on every call.  Instead only a new instance should be creating on every call:

     entry.req_rate = req_rate(RequestRate)

* There needs to be a test.

* The docstring should be updated to include the name of the class refer to the term named tuple instead of the namedtuple() factory function:

     - Returns the contents of the ``Request-rate`` parameter from
     - ``robots.txt`` in the form of a :func:`~collections.namedtuple`
     - ``(requests, seconds)``.  If there is no such parameter or it doesn't

     + Returns the contents of the ``Request-rate`` parameter from
     + ``robots.txt`` as a :term:`named tuple` ``RequestRate(requests, seconds)``.
     + If there is no such parameter or it doesn't