PHP/FI had a quirky function declaration syntax:
function sum $a, $b ( return($a + $b); );
This was changed in PHP 3, but you could continue to use the old form
in PHP 3 and PHP 4 if you declared your function as an
old_function sum $a, $b ( return($a + $b); );
Alas, after six years, this backward compatibility feature is now gone. Another nostalgic remnant of PHP/FI has passed away.