316 					$output[] = $stack->pop();
327 				while ( '(' !== ( $o2 = $stack->pop() ) ) {
340 					$arg_count = $stack->pop();
341 					$stack->pop(); // $fn
376 				while ( '(' !== ( $o2 = $stack->pop() ) ) {
390 				$stack->push( $stack->pop() + 1 );
430 					$stack->pop(); // (
431 					$stack->pop(); // 1
432 					$stack->pop(); // $fn
480 		while ( ! is_null( $op = $stack->pop() ) ) {
515 					$op1 = $stack->pop();
534 						$arg = $stack->pop();
566 						$arg = $stack->pop();
579 				$op2 = $stack->pop();
583 				$op1 = $stack->pop();
620 				$stack->push( -1 * $stack->pop() );
639 		return $stack->pop();
768 	public function pop() {  function in EvalMath_Stack