--- a/spyc/php4/5to4.php
+++ b/spyc/php4/5to4.php
@@ -1,1 +1,16 @@
+<?php
 
+php5to4 ("../spyc.php", 'spyc-latest.php4');
+
+function php5to4 ($src, $dest) {
+  $code = file_get_contents ($src);
+  $code = preg_replace ('#(public|private|protected)\s+\$#i', 'var \$', $code);
+  $code = preg_replace ('#(public|private|protected)\s+static\s+\$#i', 'var \$', $code);
+  $code = preg_replace ('#(public|private|protected)\s+function#i', 'function', $code);
+  $code = preg_replace ('#(public|private|protected)\s+static\s+function#i', 'function', $code);
+  $code = str_replace ('self::', '$this->', $code);
+  $f = fopen ($dest, 'w');
+  fwrite($f, $code);
+  fclose ($f);
+  print "Written to $dest.\n";
+}