public function decrement($key, $step)
    {
        $value = $this->getValueByKey($key, false);
        $this->alter($key, $value - $step);
    }
public function decrement($key, $step)
    {
        $value = $this->getValueByKey($key, false);
        $this->alter($key, $value - $step);
    }
public function decrement ( $ key , $ step ) { $ value = $ this -> getValueByKey ( $ key , false ) ; $ this -> alter ( $ key , $ value - $ step ) ; }
Decrements a value

@param string $key
@param integer $step
@return void
Decrements a value