docs: function jwtSignRS256(payload, privateKey) {
      var signaturePayload = JWT_RS256_HEADER + '.' + toBase64URL(JSON.stringify(payload));
  
      var rs256Signer = crypto.createSign('RSA-SHA256');
      rs256Signer.update(signaturePayload);
      var signature = toBase64URL(rs256Signer.sign(privateKey));
  
      return signaturePayload + '.' + signature;
  }