code: def proxy_route_request(self, url, environ):
          
          if self.proxy_default_timestamp:
              environ['pywb_proxy_default_timestamp'] = self.proxy_default_timestamp
  
          return self.proxy_prefix + url
docs: Return the full url that this proxy request will be routed to
          The 'environ' PATH_INFO and REQUEST_URI will be modified based on the returned url
  
          Default is to use the 'proxy_prefix' to point to the proxy collection