    async def get_all_routes(self):
        """Fetch and return all the routes associated by JupyterHub from the
        proxy.

        **Subclasses must define this method**

        Should return a dictionary of routes, where the keys are
        routespecs and each value is a dict of the form::

          {
            'routespec': the route specification ([host]/path/)
            'target': the target host URL (proto://host) for this route
            'data': the attached data dict for this route (as specified in add_route)
          }
        """
Fetch and return all the routes associated by JupyterHub from the
proxy.

**Subclasses must define this method**

Should return a dictionary of routes, where the keys are
routespecs and each value is a dict of the form::

{
'routespec': the route specification ([host]/path/)
'target': the target host URL (proto://host) for this route
'data': the attached data dict for this route (as specified in add_route)
}
jupyterhub/proxy.py