public function updateRegister($key, $value)
    {
        $this->update($key, Riak\DataType\Map::REGISTER, $value);

        return $this;
    }
public function updateRegister($key, $value)
    {
        $this->update($key, Riak\DataType\Map::REGISTER, $value);

        return $this;
    }
@param $key
@param $value

@return $this