Unable to send headers in email through sendgrid in nodejs

var header = new helper.Header({"X-Accept-Language": "en", "X-Mailer": "abc"}); var mail = new helper.Mail(from_email, subject, to_email, content, header);

HI I am trying to send email with headers {"X-Accept-Language": "en", "X-Mailer": "} but I cannot send the headers. I have attached sample code above Please let me know where I am wrong .

via Siddharth Sogani