public function getHeader($header)
    {
        $response = $this->getResponse();

        return $response->hasHeader($header) ? $response->getHeader($header)[0] : null;
    }
public function getHeader($header)
    {
        $response = $this->getResponse();

        return $response->hasHeader($header) ? $response->getHeader($header)[0] : null;
    }
public function getHeader ( $ header ) { $ response = $ this -> getResponse ( ) ; return $ response -> hasHeader ( $ header ) ? $ response -> getHeader ( $ header ) [ 0 ] : null ; }
Get response header.

@param string $header Header to fetch

@return string Header value, or a list if its more than one

@throws \RuntimeException If request hasn't been send already
Get response header .