anchor.diff:  
   fragment
   HexDigits
  -    :   HexDigit (HexDigitsAndUnderscores? HexDigit)?
  +    :   HexDigit (HexDigitOrUnderscore* HexDigit)?
       ;
   
   fragment
   HexDigit
       :   [0-9a-fA-F]
  -    ;
  -
  -fragment
  -HexDigitsAndUnderscores
  -    :   HexDigitOrUnderscore+
       ;
   
   fragment
  
positive.code:     ;
  
  enumBodyDeclarations
      :   ';' (classBodyDeclaration)*
      ;
  
  interfaceDeclaration
  
negative.code: 
  fragment
  BinaryDigits
      :   BinaryDigit (BinaryDigitOrUnderscore* BinaryDigit)?
      ;
  
  fragment
  BinaryDigit
      :   [01]
      ;
  
  fragment
  