code: function verifyStatusUpdate(exId, desiredStatus) {
          if (!desiredStatus || !_isValidStatus(desiredStatus)) {
              const error = new Error(`Invalid Job status: "${desiredStatus}"`);
              error.statusCode = 422;
              return Promise.reject(error);
          }
  
          return getStatus(exId)
              .then((status) => {
                  // when setting the same status to shouldn't throw an error
                  if (desiredStatus === status) {
                      return Promise.resolve();
                  }
  
                  // when the current status is running it cannot be set to an init status
                  if (_isRunningStatus(status) && _isInitStatus(desiredStatus)) {
                      const error = new Error(`Cannot update running job status of "${status}" to init status of "${desiredStatus}"`);
                      return Promise.reject(error);
                  }
  
                  // when the status is a terminal status, it cannot be set to again
                  if (_isTerminalStatus(status)) {
                      const error = new Error(`Cannot update terminal job status of "${status}" to "${desiredStatus}"`);
                      return Promise.reject(error);
                  }
  
                  // otherwise allow the update
                  return Promise.resolve(status);
              });
      }
docs: verify the current status to make sure it can be updated to the desired status