anchor.diff:  //     SourceCharacter but not LineTerminator
   // Must be consistent with LINE_TERMINATOR, alas ~(LINE_TERMINATOR) syntax
   // is not supported by ANTLR4
  -fragment SINGLE_LINE_COMMENT
  +fragment
  +SINGLE_LINE_COMMENT
   : '//' ~[\n\r\u2028\u2029]*
   ;
  
positive.code: //                U+202F    NARROW NO-BREAK SPACE
  //     <MMSP>     U+205F    MEDIUM MATHEMATICAL SPACE     &MediumSpace;
  //                U+3000    IDEOGRAPHIC SPACE
  fragment WHITE_SPACE
  : [\t\u000b\u000c\u0020\u00a0\ufeff\u0085\u1680\u2000-\u200a\u202f\u205f\u3000]
  ;
  
  
negative.code: //     <CR>     U+000D    CARRIAGE RETURN
  //     <LS>     U+2028    LINE SEPARATOR
  //     <PS>     U+2029    PARAGRAPH SEPARATOR
  fragment
  LINE_TERMINATOR
  : [\n\r\u2028\u2029]
  ;
  
  