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: cron.go
    path of file: ./repos/coder/coderd/schedule/cron
    
    the code of the file until where you have to start completion: // package schedule provides utilities for managing template and workspace
// autostart and autostop schedules. This includes utilities for parsing and
// deserializing cron-style expressions.
package cron

impo
    
func validateWeeklySpec(spec string) error {
	parts := strings.Fields(spec)
	if len(parts) < 5 {
		return xerrors.Errorf("expected schedule to consist of 5 fields with an optional CRON_TZ=<timezone> prefix")
	}
	if len(parts) == 6 {
		parts = parts[1:]
	}
	if parts[2] != "*" || parts[3] != "*" {
		return xerrors.Errorf("expected day-of-month and month to be *")
	}
	return nil
}