<STRING> "\\t" => (addString "\t" ; lex() );
<STRING> "\\\"" => (addString "\t" ; lex() );
<STRING> "\\". => (ErrorMsg.error (ParseState.ext (yypos,yypos))
<STRING> "\\t" => (addString "\t" ; lex() );
<STRING> "\\\"" => (addString "\t" ; lex() );
<STRING> "\\". => (ErrorMsg.error (ParseState.ext (yypos,yypos))