docs: def fromRequest(cls, store, request):
          """
          Return a L{LoginPage} which will present the user with a login prompt.
  
          @type store: L{Store}
          @param store: A I{site} store.
  
          @type request: L{nevow.inevow.IRequest}
          @param request: The HTTP request which encountered a need for
              authentication.  This will be effectively re-issued after login
              succeeds.
  
          @return: A L{LoginPage} and the remaining segments to be processed.
          """
          location = URL.fromRequest(request)
          segments = location.pathList(unquote=True, copy=False)
          segments.append(request.postpath[0])
          return cls(store, segments, request.args)