code: func (c *QECombiner) GetState(namespace string, key string) ([]byte, error) {
  	var vv *statedb.VersionedValue
  	var val []byte
  	var err error
  	for _, qe := range c.QueryExecuters {
  		if vv, err = qe.GetState(namespace, key); err != nil {
  			return nil, err
  		}
  		if vv != nil {
  			if !vv.IsDelete() {
  				val = vv.Value
  			}
  			break
  		}
  	}
  	return val, nil
  }
docs: // GetState implements function in the interface ledger.SimpleQueryExecutor