<YYINITIAL> isvalid { return tok(Sym.ISVALID, yytext()); }
<YYINITIAL> for { return tok(Sym.FOR, yytext()); }
<YYINITIAL> to { return tok(Sym.TO, yytext()); }
+<YYINITIAL> this { return tok(Sym.THIS, yytext()); }
<YYINITIAL> structure { return tok(Sym.STRUCTURE, yytext()); }
<YYINITIAL> reserved { return tok(Sym.RESERVED, yytext()); }