anchor.diff:  COMMENT
       : '--[' NESTED_STR ']' -> channel(HIDDEN)
       ;
  -    
  +
   LINE_COMMENT
       : '--'
       (                                               // --
  
positive.code:     ;
  
  NORMALSTRING
      : '"' ( EscapeSequence | ~('\\'|'"') )* '"' 
      ;
  
  CHARSTRING
  
negative.code: 
  Tested by Kazunori Sakamoto with Test suite for Lua 5.2 (http://www.lua.org/tests/5.2/)
  
  Tested by Alexander Alexeev with Test suite for Lua 5.3 http://www.lua.org/tests/lua-5.3.2-tests.tar.gz
  */
  
  grammar Lua;
  