array(1) {
  ["OAuth_signature_does_not_match"]=>
  string(0) ""
}
<h3><a href="https://ultherapy.com/oauth1/authorize? OAuth signature does not match&oauth_callback=http%3A%2F%2Fultherapy.test%2FWP_API_OAuth_Test_client.php">LOGIN USING YOUR https://ultherapy.com WORDPRESS ACCOUNT</a></h3>Uses WP-API and OAuth 1.0a Server for WordPress via https://github.com/WP-API