def METHOD_NAME(self, ip, n):
    sh = vd.importExternal('sh')
    while n > len(self.routes[ip]):
        self.routes[ip].append(None)
    sh.traceroute('--sim-queries=1',
                  '--queries=1',
                  '--first=%s' % n,
                  '--max-hops=%s' % n,
                  ip,
                  _bg=True, _bg_exc=False,
                  _out=lambda data,self=self,ip=ip,a=1: self.traceroute_response(ip, data),
                  _err=lambda data,self=self,ip=ip,a=1: self.ping_error(ip, data))