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: worker.go
    path of file: ./repos/juju/worker/leaseexpiry
    
    the code of the file until where you have to start completion: // Copyright 2022 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package lease
    
func NewWorker(cfg Config) (worker.Worker, error) {
	var err error

	if err = cfg.Validate(); err != nil {
		return nil, errors.Trace(err)
	}

	w := &expiryWorker{
		clock:     cfg.Clock,
		logger:    cfg.Logger,
		trackedDB: cfg.TrackedDB,
		dml: `
DELETE FROM lease WHERE uuid in (
    SELECT l.uuid 
    FROM   lease l LEFT JOIN lease_pin p ON l.uuid = p.lease_uuid
    WHERE  p.uuid IS NULL
    AND    l.expiry < datetime('now')
)`[1:],
	}

	w.tomb.Go(w.loop)
	return w, nil

}