code: func (e *elementBase) writeChildren(bf *bytes.Buffer) (int64, error) {
  	l := len(e.children)
  	for index, child := range e.children {
  		if index == l-1 {
  			child.SetLastChild(true)
  		}
  
  		if e.opts.formatter != nil {
  			if i, err := e.opts.formatter.OpeningElement(bf, child); err != nil {
  				return int64(i), err
  			}
  		}
  		if i, err := child.WriteTo(bf); err != nil {
  			return int64(i), err
  		}
  	}
  	return 0, nil
  }
docs: // writeChildren writes the children's HTML.