code: function isOk(err, res, body) {
      if (err) {
        return callback(err);
      }
  
      var statusCode = res.statusCode.toString(),
          error;
  
      //
      //  Emit response for debug purpose
      //
      self.emit('debug::response', { statusCode: statusCode, result: body });
  
      if (Object.keys(self.failCodes).indexOf(statusCode) !== -1) {
        error = new Error('composer Error (' + statusCode + '): ' + self.failCodes[statusCode]);
        if (body) {
          try { error.result = JSON.parse(body) }
          catch (ex) {}
        }
        error.status = res.statusCode;
        callback(error);
        return false
      }
  
      return true;
    }
docs: Helper function for checking response codes