anchor.diff:      ;
   
   specifiedVariable
  -    : variable^ specifier
  +    : variable^ specifier?
       ;
   
   variable2
  
positive.code:     ;
  
  tryBlock
      : 'try'^ ('('! specifiedVariableOrExpression ')'!)? block
      ;
  
  catchBlock
  
negative.code:     : 'finally'^ block
      ;
  
  resource
      : ('@'|declarationStart|specificationStart) => specifiedVariable2
      -> ^(RESOURCE specifiedVariable2)
      | expression
      -> ^(RESOURCE expression)
      ;
  