(Program
{ (Comparison
  {-(Send
    {-(Identifier)-})-}
  {-(Send
    {-(Identifier)-})-})
->(Equal
  {+(Send
    {+(Identifier)+})+}
  {+(Send
    {+(Identifier)+})+}) }
{+(Not
  {+(Equal
    {+(Send
      {+(Identifier)+})+}
    {+(Send
      {+(Identifier)+})+})+})+}
{+(Equal
  {+(Send
    {+(Identifier)+})+}
  {+(Send
    {+(Identifier)+})+})+}
{-(Matches
  {-(Send
    {-(Identifier)-})-}
  {-(Send
    {-(Identifier)-})-})-}
{-(Assignment
  {-(Identifier)-}
  {-(Not
    {-(Send
      {-(Identifier)-})-})-})-})