public function getRequirement($key)
    {
        return isset($this->requirements[$key]) ? $this->requirements[$key] : null;
    }
public function getRequirement($key)
    {
        return isset($this->requirements[$key]) ? $this->requirements[$key] : null;
    }
public function getRequirement ( $ key ) { return isset ( $ this -> requirements [ $ key ] ) ? $ this -> requirements [ $ key ] : null ; }
Returns the requirement for the given key.

@param string $key The key

@return string|null The regex or null when not given
Returns the requirement for the given key .