private function createOAuthHeaders($nonce, $timestamp, $hash)
    {
        $oauth_header = [];
        $oauth_header[] = 'oauth_consumer_key="' . $this->key . '"';
        $oauth_header[] = 'oauth_nonce="' . $nonce . '"';
        $oauth_header[] = 'oauth_signature="' . $hash . '"';
        $oauth_header[] = 'oauth_signature_method="HMAC-SHA256"';
        $oauth_header[] = 'oauth_timestamp="' . $timestamp . '"';
        $oauth_header[] = 'oauth_version="1.0"';
        return $oauth_header;
    }