anchor.diff:      ;
   
   constantExpression
  -    :   conditionalExpression
  -    ;
  -
  -declaration
  -    :   declarationSpecifiers initDeclaratorList ';'
  -	| 	declarationSpecifiers ';'
  -    ;
  -
  -declarationSpecifiers
  -    :   declarationSpecifier+
  -    ;
  -
  -declarationSpecifier
  -    :   typeSpecifier
  -    ;
  -
  -initDeclaratorList
  -    :   initDeclarator
  -    |   initDeclaratorList ',' initDeclarator
  -    ;
  -
  -initDeclarator
  -    :   declarator
  -    |   declarator '=' initializer
  -    ;
  -
  -typeSpecifier
  -    :   typeName
  -    ;
  -
  -specifierQualifierList
  -    :   typeSpecifier specifierQualifierList?
  -    ;
  +    :   Constant
  +    ;
  +
  +//initDeclaratorList
  +//    :   initDeclarator
  +//    |   initDeclaratorList ',' initDeclarator
  +//    ;
  +//
  +//initDeclarator
  +//    :   declarator
  +//    |   declarator '=' initializer
  +//    ;
   
   enumSpecifier
       :   'enum' Identifier '{' enumeratorList '}'
  
positive.code: 
  blockItem
      :   statement
      |   declaration
      ;
  
  expressionStatement
  
negative.code: assignmentExpression
      :   conditionalExpression
      |   unaryExpression assignmentOperator assignmentExpression
      ;
  
  assignmentOperator
  