code: function( hmacAlgoRaw, hmacKeyRaw, ftnreq ) {
          // this.hmacbase = '';
          const hmac = crypto.createHmac( hmacAlgoRaw, hmacKeyRaw );
  
          _hmacUpdate( hmac, ftnreq, 'sec' );
          return hmac.digest();
      }
docs: Gen HMAC through .update() ---- /* istanbul ignore next