private static function serializeHeaders(array $headers)
    {
        $resultString = "Headers:\n";
        foreach ($headers as $key => $value) {
            $resultString .= sprintf("%s: %s\n", $key, $value[0]);
        }

        return $resultString;
    }
private static function serializeHeaders(array $headers)
    {
        $resultString = "Headers:\n";
        foreach ($headers as $key => $value) {
            $resultString .= sprintf("%s: %s\n", $key, $value[0]);
        }

        return $resultString;
    }
private static function serializeHeaders ( array $ headers ) { $ resultString = "Headers:\n" ; foreach ( $ headers as $ key => $ value ) { $ resultString .= sprintf ( "%s: %s\n" , $ key , $ value [ 0 ] ) ; } return $ resultString ; }
Serialize the message headers.

@param  array  $headers The headers to be serialized.

@return string
Serialize the message headers .