...

=over 4

=item $url = $input->url

Return the URL of the input document, if it is known, or C<undef>
otherwise.  If the request has been redirected, then the URL
of the final document is returned.  What being returned by this
attribute is a string.

=item $input->add_url ($url)

Add the URL specified as a string I<$url> to the end of the list of URLs
for the input.  If there exists other URLs in the list of URLs for the
input, then it represents that the request to obtain the resource for
the last URL has been redirected to the URL I<$url>.

=item $urls = $input->urls

Return a reference to an array that contains the URLs in the list of URLs,
preserving order of them.  The array may be empty.

=back

...