docs: function run(callback) {
          invariant(!Router.isRunning, 'Router is already running');
  
          dispatchHandler = function (error, transition, newState) {
            if (error) Router.handleError(error);
  
            if (pendingTransition !== transition) return;
  
            pendingTransition = null;
  
            if (transition.abortReason) {
              Router.handleAbort(transition.abortReason);
            } else {
              callback.call(Router, Router, nextState = newState);
            }
          };
  
          if (!(location instanceof StaticLocation)) {
            if (location.addChangeListener) location.addChangeListener(Router.handleLocationChange);
  
            Router.isRunning = true;
          }
  
          // Bootstrap using the current path.
          Router.refresh();
        }