anchor.diff:      : IMPORT
         { $importModule = new ImportModule($IMPORT); }
         ( 
  -        q1=STRING_MID
  +        q1=CHAR_LITERAL
           { $importModule.setQuotedLiteral(new QuotedLiteral($q1)); }
         |
           packagePath
           { $importModule.setImportPath($packagePath.importPath); }
         )
  -      q2=STRING_MID
  +      q2=CHAR_LITERAL
         { $importModule.setVersion(new QuotedLiteral($q2)); 
           expecting=SEMICOLON; }
         SEMICOLON
  
positive.code: */
  fragment
  StringPart
      : ( ~ ('\\' | '"' | '\'') | EscapeSequence )*
      ;
      
  fragment
  
negative.code:       { $literal = new NaturalLiteral($NATURAL_LITERAL); }
      | FLOAT_LITERAL 
        { $literal = new FloatLiteral($FLOAT_LITERAL); }
      | CHAR_LITERAL 
        { $literal = new CharLiteral($CHAR_LITERAL); }
      ;
  
  stringLiteral returns [StringLiteral stringLiteral]
  