code: Expr mulDivMod() {
  		Expr expr = nullSafe();
  		for (Tok tok=peek(); tok.sym==Sym.MUL || tok.sym==Sym.DIV || tok.sym==Sym.MOD; tok=peek()) {
  			move();
  			expr = new Arith(tok.sym, expr, nullSafe(), location);
  		}
  		return expr;
  	}
docs: mulDivMod : expr ('*'|'/'|'%') expr