code/libraries/joomlatools/library/http/message/headers.php
public function offsetExists($key)
    {
        $key = strtr(strtolower($key), '_', '-');

        return array_key_exists($key, $this->_data);
    }
public function offsetExists($key)
    {
        $key = strtr(strtolower($key), '_', '-');

        return array_key_exists($key, $this->_data);
    }
public function offsetExists ( $ key ) { $ key = strtr ( strtolower ( $ key ) , '_' , '-' ) ; return array_key_exists ( $ key , $ this -> _data ) ; }
Test existence of a key

@param  string  $key The key name
@return boolean
Test existence of a key