'Provides a url that can be queried. If we have multiple endpoints then one
will be picked randomly.
:param bool use_authority: ignores our endpoints and uses a directory
authority instead
:returns: **str** for the url being queried by this request'

def _pick_url(self, use_authority=False):

    if (use_authority or (not self.endpoints)):
        authority = random.choice(filter(HAS_V3IDENT, get_authorities().values()))
        (address, dirport) = (authority.address, authority.dir_port)
    else:
        (address, dirport) = random.choice(self.endpoints)
    return ('http://%s:%i/%s' % (address, dirport, self.resource.lstrip('/')))
