WC_Emails::email_header PHP Method

    public function email_header($email_heading)
    {
        wc_get_template('emails/email-header.php', array('email_heading' => $email_heading));
    }

 public function trigger($recipient, $subject, $content, $attachment = array())
 {
     /* global $woocommerce; */
     $mail = new WC_Emails();
     $email_heading = get_bloginfo('name');
     ob_start();
     $mail->email_header($email_heading);
     $message = ob_get_clean();
     $message .= $content;
     ob_start();
     $mail->email_footer();
     $message .= ob_get_clean();
     $mail->send($recipient, $subject, $message, "Content-Type: text/html\r\n", $attachment);
 }