anchor.diff:  /*
    [The "BSD licence"]
  - Copyright (c) 2016 Sasa Coh
  + Copyright (c) 2017 Sasa Coh, Michał Błotniak
    All rights reserved.
   
    Redistribution and use in source and binary forms, with or without
  
positive.code:     ;
  
  
  fragment LETTER : UNICODE_LETTER | '_'
      ;
  
  fragment DECIMAL_DIGIT : [0-9]
      ;
  
  fragment OCTAL_DIGIT   : [0-7]
      ;
  
  fragment HEX_DIGIT     : [0-9a-fA-F]
      ;
  
  fragment NEWLINE        : [\u000A] ; /* the Unicode code point U+000A */
  fragment UNICODE_CHAR   : ~[\u000A] ; /* an arbitrary Unicode code point except newline */
  //UNICODE_LETTER : ; /* a Unicode code point classified as "Letter" */ .
  //UNICODE_DIGIT  : ; /* a Unicode code point classified as "Number, decimal digit" */ .
  
  fragment UNICODE_DIGIT
   : [\u0030-\u0039]
   | [\u0660-\u0669]
  
negative.code: // LEXER
  
  
  // Identifiers
  //identifier = letter { letter | unicode_digit } .
  IDENTIFIER
      : LETTER ( LETTER | UNICODE_DIGIT )*
      ;
  
  // Keywords
  KEYWORD
      : 'break'
      | 'default'
  