code: func (l *kvLedger) GetBlockByHash(blockHash []byte) (*common.Block, error) {
  	block, err := l.blockStore.RetrieveBlockByHash(blockHash)
  	l.blockAPIsRWLock.RLock()
  	l.blockAPIsRWLock.RUnlock()
  	return block, err
  }
docs: // GetBlockByHash returns a block given it's hash