code: func DateTrunc(db XODB, v0 string, v1 time.Time, v2 string, v3 time.Time, v4 string, v5 *time.Duration) (time.Time, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT pg_catalog.date_trunc($1, $2, $3, $4, $5, $6)`
  
  	// run query
  	var ret time.Time
  	XOLog(sqlstr, v0, v1, v2, v3, v4, v5)
  	err = db.QueryRow(sqlstr, v0, v1, v2, v3, v4, v5).Scan(&ret)
  	if err != nil {
  		return time.Time{}, err
  	}
  
  	return ret, nil
  }
docs: // DateTrunc calls the stored procedure 'pg_catalog.date_trunc(text, timestamp without time zone, text, timestamp with time zone, text, interval) timestamp without time zone' on db.