code: Expr equalNotEqual() {
  		Expr expr = greaterLess();
  		for (Tok tok=peek(); tok.sym==Sym.EQUAL || tok.sym==Sym.NOTEQUAL; tok=peek()) {
  			move();
  			expr = new Compare(tok.sym, expr, greaterLess(), location);
  		}
  		return expr;
  	}
docs: equalNotEqual : expr ('==' | '!=') expr