code: func GinCmpPrefix(db XODB, v0 string, v1 string, v2 int16, v3 pgtypes.Internal) (int, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT pg_catalog.gin_cmp_prefix($1, $2, $3, $4)`
  
  	// run query
  	var ret int
  	XOLog(sqlstr, v0, v1, v2, v3)
  	err = db.QueryRow(sqlstr, v0, v1, v2, v3).Scan(&ret)
  	if err != nil {
  		return 0, err
  	}
  
  	return ret, nil
  }
docs: // GinCmpPrefix calls the stored procedure 'pg_catalog.gin_cmp_prefix(text, text, smallint, internal) integer' on db.