m[2] is the third element of m, rather than the second, so we have to
check instead that the len of m is at least 3.
Because the regular expression has two capture groups, the length of m
will always be 3, so currently the guard will always be true.
Most endpoints respect this parameter by default. Those that don't will
just ignore it. The `per_page=100` parameter is not added if there is
already a `per_page` parameter specified in the request.