code: func (c *Client) RescanBlocksAsync(blockHashes []chainhash.Hash) FutureRescanBlocksResult {
  	strBlockHashes := make([]string, len(blockHashes))
  	for i := range blockHashes {
  		strBlockHashes[i] = blockHashes[i].String()
  	}
  
  	cmd := btcjson.NewRescanBlocksCmd(strBlockHashes)
  	return c.sendCmd(cmd)
  }
docs: // RescanBlocksAsync 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 RescanBlocks for the blocking version and more details.
  //
  // NOTE: This is a btcsuite extension ported from
  // github.com/decred/dcrrpcclient.