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: asequence.xo.go
    path of file: ./repos/xo/_examples/a_bit_of_everything/oracle
    
    the code of the file until where you have to start completion: package oracle

// Code generated by xo. DO NOT EDIT.

import (
	"context"
	"database/sql"
)

// ASequence represents a row from 'a_bit_of_everything.a_sequence'.
type ASequence struct {
	ASeq int `json:"a_seq"` // a_seq
	// xo fields
	_exists, _deleted bool
}

// Exists returns true when the [ASequence] exists in
    
func (as *ASequence) Insert(ctx context.Context, db DB) error {
	switch {
	case as._exists: // already exists
		return logerror(&ErrInsertFailed{ErrAlreadyExists})
	case as._deleted: // deleted
		return logerror(&ErrInsertFailed{ErrMarkedForDeletion})
	}
	// insert (primary key generated and returned by database)
	const sqlstr = `INSERT INTO a_bit_of_everything.a_sequence (` +
		`` +
		`) VALUES (` +
		`` +
		`) RETURNING a_seq INTO :1`
	// run
	logf(sqlstr)
	var id int64
	if _, err := db.ExecContext(ctx, sqlstr, sql.Out{Dest: &id}); err != nil {
		return logerror(err)
	} // set primary key
	as.ASeq = int(id)
	// set exists
	as._exists = true
	return nil
}