BINARY_OP
| expr '<' expr { BINARY_OP($$, <, $1, $3); }
| expr '>' expr { BINARY_OP($$, >, $1, $3); }
| expr '+' expr { BINARY_OP($$, +, $1, $3); }
| expr '-' expr { BINARY_OP($$, -, $1, $3); }
| expr '*' expr { BINARY_OP($$, *, $1, $3); }