code: func (c *Client) ListSinceBlockMinConfAsync(blockHash *chainhash.Hash, minConfirms int) FutureListSinceBlockResult {
  	var hash *string
  	if blockHash != nil {
  		hash = btcjson.String(blockHash.String())
  	}
  
  	cmd := btcjson.NewListSinceBlockCmd(hash, &minConfirms, nil)
  	return c.sendCmd(cmd)
  }
docs: // ListSinceBlockMinConfAsync 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 ListSinceBlockMinConf for the blocking version and more details.