code: public final S getClosestContainerScope() {
      S scope = getClosestHoistScope();
      if (scope.isBlockScope()) {
        scope = scope.getParent();
        checkState(!scope.isBlockScope());
      }
      return scope;
    }
docs: Returns the closest container scope. This is equivalent to what the current scope would have
  been for non-ES6 scope creators, and is thus useful for migrating code to use block scopes.