anchor.diff:          $condition.setVariable($impliedVariable.variable); }
       //-> ^(EXISTS_CONDITION[$EXISTS] impliedVariable)
       | LPAREN e2=EXISTS 
  -      { $condition = new ExistsCondition($e2); } 
  +      ({ $condition = new ExistsCondition($e2); } 
         specifiedVariable 
  -      { $condition.setVariable($specifiedVariable.variable); }
  +      { $condition.setVariable($specifiedVariable.variable); })?
         RPAREN
       //-> ^(EXISTS_CONDITION[$EXISTS] specifiedVariable2)
       ;
  
positive.code:         $condition.setVariable($impliedVariable.variable); }
      //-> ^(NONEMPTY_CONDITION[$NONEMPTY] impliedVariable)
      | LPAREN n2=NONEMPTY 
        { $condition = new NonemptyCondition($n2); }
        specifiedVariable 
        { $condition.setVariable($specifiedVariable.variable); }
        RPAREN
      //-> ^(NONEMPTY_CONDITION[$NONEMPTY] specifiedVariable2)
      ;
  
negative.code:       memberName
        { $condition.getVariable().setIdentifier($memberName.identifier); }
        specifier
        { $condition.getVariable().setSpecifierExpression($specifier.specifierExpression); })?
        RPAREN
      //-> ^(IS_CONDITION[$IS_OP] unionType ^(VARIABLE unionType memberName specifier))
      ;
  