anchor.diff:  
   fragment
   NonStringChars
  -    :    '\\' | '"' | '\''
  +    :    '\\' | '"'
       ;
   
   fragment
   StringPart
  -    : ( ~ /* NonStringChars*/ ('\\' | '"' | '\'')
  +    : ( ~ /* NonStringChars*/ ('\\' | '"')
       | EscapeSequence) *
       ;
       
  
positive.code:         |   'n'
          |   'f'
          |   'r'
          |   '"'
          |   '\''
          |   '`'
  
negative.code:     ;
  
  QUOTEDLITERAL
      :   '\'' QuotedLiteralPart '\''
      ;
  
  fragment
  QuotedLiteralPart
      : ~('\'')
      ;
  
  SIMPLESTRINGLITERAL
  