code: func newElementBase(ln *line, rslt *result, src *source, parent element, opts *Options) elementBase {
  	return elementBase{
  		ln:     ln,
  		rslt:   rslt,
  		src:    src,
  		parent: parent,
  		opts:   opts,
  	}
  }
docs: // newElementBase creates and returns an element base.