code: func (s *InjectedStore) BeginWithStartTS(startTS uint64) (Transaction, error) {
  	txn, err := s.Storage.BeginWithStartTS(startTS)
  	return &InjectedTransaction{
  		Transaction: txn,
  		cfg:         s.cfg,
  	}, err
  }
docs: // BeginWithStartTS creates an injected Transaction with startTS.