Basho\Riak\Command\Builder\UpdateHll::add PHP Method

    public function add($element)
    {
        settype($element, 'string');
        $this->add_all[] = $element;
        return $this;
    }

 /**
  * Tests validate properly verifies the Bucket is not there
  *
  * @expectedException \Basho\Riak\Command\Builder\Exception
  */
 public function testValidateBucket()
 {
     $builder = new Command\Builder\UpdateHll(static::$riak);
     $builder->add('some_element');
     $builder->build();
 }