Write a PHP program to concat two given strings. If the given strings have different length remove the characters from the longer string

<?php
function test($s1, $s2)
 { 
     if (strlen($s1) < strlen($s2))
       {
          return $s1 . substr($s2, strlen($s2) - strlen($s1));
       }
     else if (strlen($s1) > strlen($s2))
       {
           return  substr($s1, strlen($s1) - strlen($s2)) . $s2;
       }
     else
       {
          return $s1 . $s2;
       }
 }

echo test("abc", "abcd") . "\n";
echo test("Python", "Python") . "\n";
echo test("JS", "Python") . "\n";