code: func GenCassandra(u *URL) (string, error) {
  	host, port, dbname := "localhost", "9042", strings.TrimPrefix(u.Path, "/")
  	if h := hostname(u.Host); h != "" {
  		host = h
  	}
  	if p := hostport(u.Host); p != "" {
  		port = p
  	}
  	q := u.Query()
  	// add user/pass
  	if u.User != nil {
  		q.Set("username", u.User.Username())
  		if pass, _ := u.User.Password(); pass != "" {
  			q.Set("password", pass)
  		}
  	}
  	// add dbname
  	if dbname != "" {
  		q.Set("keyspace", dbname)
  	}
  	return host + ":" + port + genQueryOptions(q), nil
  }
docs: // GenCassandra generates a cassandra DSN from the passed URL.