(Program
  (Call
    (Identifier)
  {+(Identifier)+}
    (Identifier)
    (Empty))
{+(Call
  {+(Identifier)+}
  {+(Identifier)+}
  {+(Empty)+})+}
{+(Context
  {+(Comment)+}
  {+(Empty)+})+}
{-(Context
  {-(Comment)-}
  {-(Call
    {-(Identifier)-}
    {-(Identifier)-}
    {-(Identifier)-}
    {-(Empty)-})-})-})