anchor.diff:      ;
   
   directive
  -    : 'return' assignable? 
  -    | 'throw' expression? 
  -    | 'break' expression?
  -    | 'retry'
  +    : return | throw | break | retry
  +    ;
  +
  +return
  +    : 'return' assignable?
  +    ;
  +
  +throw
  +    : 'throw' expression?
  +    ;
  +
  +break
  +    : 'break' expression?
  +    ;
  +    
  +retry
  +    : 'retry'
       ;
   
   abstractMemberDeclaration
  
positive.code:     ;
      
  typeDeclaration
      : classDeclaration 
      | interfaceDeclaration
      | aliasDeclaration
      ;
  
negative.code:     : parameterizedType //( '[' parameterizedType? ']' )?
      | 'subtype'
      ;
  
  parameterizedType
      : qualifiedTypeName typeArguments?
      ;
  