code: func (fs *FSLocalKeyStore) GetKnownHostKeys(hostname string) ([]ssh.PublicKey, error) {
  	bytes, err := ioutil.ReadFile(filepath.Join(fs.KeyDir, fileNameKnownHosts))
  	if err != nil {
  		if os.IsNotExist(err) {
  			return nil, nil
  		}
  		return nil, trace.Wrap(err)
  	}
  	var (
  		pubKey    ssh.PublicKey
  		retval    []ssh.PublicKey = make([]ssh.PublicKey, 0)
  		hosts     []string
  		hostMatch bool
  	)
  	for err == nil {
  		_, hosts, pubKey, _, bytes, err = ssh.ParseKnownHosts(bytes)
  		if err == nil {
  			hostMatch = (hostname == "")
  			if !hostMatch {
  				for i := range hosts {
  					if hosts[i] == hostname {
  						hostMatch = true
  						break
  					}
  				}
  			}
  			if hostMatch {
  				retval = append(retval, pubKey)
  			}
  		}
  	}
  	if err != io.EOF {
  		return nil, trace.Wrap(err)
  	}
  	return retval, nil
  }
docs: // GetKnownHostKeys returns all known public keys from 'known_hosts'