You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: export.go
    path of file: ./repos/gen/field
    
    the code of the file until where you have to start completion: package field

import (
	"fmt"
	"strings"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

var (
	// Star a symbol of "*"
	Star = NewAsterisk("")
	// ALL same with Star
	ALL = Star
)

// Option field option
type Option func(clause.Column) clause.Column

var (
	banColumnRaw Option = func(col clause.Column) clause.Column {
		col.Raw = false
		return col
	}
)

// ======================== generic field =======================

// NewField create new field
f
    
func ContainsSubQuery(columns []Expr, subQuery *gorm.DB) Expr {
	switch len(columns) {
	case 0:
		return expr{e: clause.Expr{}}
	case 1:
		return expr{e: clause.Expr{
			SQL:  "? IN (?)",
			Vars: []interface{}{columns[0].RawExpr(), subQuery},
		}}
	default: // len(columns) > 0
		placeholders := make([]string, len(columns))
		cols := make([]interface{}, len(columns))
		for i, c := range columns {
			placeholders[i], cols[i] = "?", c.RawExpr()
		}
		return expr{e: clause.Expr{
			SQL:  fmt.Sprintf("(%s) IN (?)", strings.Join(placeholders, ",")),
			Vars: append(cols, subQuery),
		}}
	}
}