code: func (c *Client) VersionAsync() FutureVersionResult {
  	cmd := btcjson.NewVersionCmd()
  	return c.sendCmd(cmd)
  }
docs: // VersionAsync 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 Version for the blocking version and more details.
  //
  // NOTE: This is a btcsuite extension ported from
  // github.com/decred/dcrrpcclient.