code: function History (router, base) {
    this.router = router;
    this.base = normalizeBase(base);
    // start with a route object that stands for "nowhere"
    this.current = START;
    this.pending = null;
    this.ready = false;
    this.readyCbs = [];
    this.readyErrorCbs = [];
    this.errorCbs = [];
  }
docs: /*