anchor.diff:  DollarDollarEscape
       :   '$$'
       ;
  +
   // §3.10.7 The Null Literal
  -
   NullLiteral
       :   'null'
       ;
  
positive.code: 
  fragment
  BinaryNumeral
      :   '0' [bB] BinaryDigits
      ;
  
  fragment
  
negative.code: 
  fragment
  HexNumeral
      :   Zero [xX] HexDigits
      ;
  
  fragment
  