public function getLocations() {
    $locations = [];

    $cid = __METHOD__;
    if ($cache = $this->cache->get($cid)) {
      return $cache->data;
    }

    $branches = $this->client->getBranches(['limit' => 100]);
    foreach ($branches as $branch) {
      $locations[$branch->id] = $branch->name;
    }

    $this->cache->set($cid, $locations);
    return $locations;
  }