presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraTable.java/CassandraTable/getTokenExpression
class CassandraTable:    public String getTokenExpression()
    {
        StringBuilder sb = new StringBuilder();
        for (CassandraColumnHandle column : getPartitionKeyColumns()) {
            if (sb.length() == 0) {
                sb.append("token(");
            }
            else {
                sb.append(",");
            }
            sb.append(CassandraCqlUtils.validColumnName(column.getName()));
        }
        sb.append(")");
        return sb.toString();
    }