<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_page(self, route, target, link_name=None):
 """Add a new proxied page to the Web UI. Parameters route : str The route for the proxied page. Must be a valid path *segment* in a url (e.g. ``foo`` in ``/foo/bar/baz``). Routes must be unique across the application. target : str The target address to be proxied to this page. Must be a valid url. link_name : str, optional If provided, will be the link text used in the Web UI. If not provided, the page will still be proxied, but no link will be added to the Web UI. Link names must be unique across the application. Returns ------- ProxiedPage """

        req = proto.Proxy(route=route, target=target, link_name=link_name)
        self._client._call('AddProxy', req)
        return ProxiedPage(route, target, link_name, self.address,
                           self.proxy_prefix)