(Program
{+(Call
  {+(Identifier)+}
  {+(TextElement)+}
  {+(Empty)+})+}
  (Call
    (Identifier)
    (TextElement)
  {+(Null)+}
  {-(Identifier)-}
    (Empty))
  (Call
    (Identifier)
    (TextElement)
  {+(Identifier)+}
    (Identifier)
  {-(Identifier)-}
    (Empty))
{-(Call
  {-(Identifier)-}
  {-(TextElement)-}
  {-(Empty)-})-})