public function addHeader($key, $value)
    {
        $this->options[GuzzleRequestOptions::HEADERS][$key] = $value;

        return $this;
    }
public function addHeader($key, $value)
    {
        $this->options[GuzzleRequestOptions::HEADERS][$key] = $value;

        return $this;
    }
public function addHeader ( $ key , $ value ) { $ this -> options [ GuzzleRequestOptions :: HEADERS ] [ $ key ] = $ value ; return $ this ; }
Headers to add to the request.

@param $key
@param $value

@return $this
Headers to add to the request .