code: func NewReadGroup(name, center, desc, lib, prog, plat, unit, sample, flow, key string, date time.Time, size int) (*ReadGroup, error) {
  	if !validInt32(size) {
  		return nil, errors.New("sam: length overflow")
  	}
  	return &ReadGroup{
  		id:           -1, // This is altered by a Header when added.
  		name:         name,
  		center:       center,
  		description:  desc,
  		date:         date,
  		flowOrder:    flow,
  		keySeq:       key,
  		library:      lib,
  		program:      prog,
  		insertSize:   size,
  		platform:     plat,
  		platformUnit: unit,
  		sample:       sample,
  	}, nil
  }
docs: // NewReadGroup returns a ReadGroup with the given name, center, description,
  // library, program, platform, unique platform unit, sample name, flow order,
  // key, date of read group production, and predicted median insert size sequence.