code: func (c *Client) GetTxOutAsync(txHash *chainhash.Hash, index uint32, mempool bool) FutureGetTxOutResult {
  	hash := ""
  	if txHash != nil {
  		hash = txHash.String()
  	}
  
  	cmd := btcjson.NewGetTxOutCmd(hash, index, &mempool)
  	return c.sendCmd(cmd)
  }
docs: // GetTxOutAsync returns an instance of a type that can be used to get
  // the result of the RPC at some future time by invoking the Receive function on
  // the returned instance.
  //
  // See GetTxOut for the blocking version and more details.