Basho\Riak\Object::addValueToIndex PHP Method

    public function addValueToIndex($indexName, $value)
    {
        $this->validateIndexNameAndValue($indexName, $value);
        if (!isset($this->indexes[$indexName])) {
            $this->indexes[$indexName] = [];
        }
        $this->indexes[$indexName][] = $value;
        return $this;
    }

 public function testStoreObjectWithIndexes()
 {
     $object = new RObject('person');
     $object->addValueToIndex('lucky_numbers_int', 42);
     $object->addValueToIndex('lucky_numbers_int', 64);
     $object->addValueToIndex('lastname_bin', 'Knuth');
     $command = (new Command\Builder\StoreObject(static::$riak))->withObject($object)->buildLocation(static::$key, 'Users', static::LEVELDB_BUCKET_TYPE)->build();
     $response = $command->execute();
     $this->assertEquals('204', $response->getCode());
 }