protected function conditionalSet($key, $value)
    {
        if (!$this->has($key)) {
            $this->set($key, $value);
        }
    }
protected function conditionalSet($key, $value)
    {
        if (!$this->has($key)) {
            $this->set($key, $value);
        }
    }
protected function conditionalSet ( $ key , $ value ) { if ( ! $ this -> has ( $ key ) ) { $ this -> set ( $ key , $ value ) ; } }
Set a value in a container only if it is not defined already.

@param string $key
@param mixed $value
Set a value in a container only if it is not defined already .