Fatal error: Cannot redeclare MYTHEME_preprocess_user_picture() If I add the following:

      function MYTHEME_preprocess_user_picture(&amp;$variables) { 
      $variables['user_picture'] = theme('image_style', array('style_name' =&gt; 'thumbnail_scale_n_crop_120_x_120', 'path' =&gt; $filepath, 'alt' =&gt; $alt, 'title' =&gt; $alt));
}


to my comment.tpl.php (the purpose of which is to use an image style on the comment author's picture,) I get a WSOD with the following message:

Fatal error: Cannot redeclare MYTHEME_preprocess_user_picture() (previously declared in /home3/zc1/public_html/sites/all/themes/mytheme/comment.tpl.php:8) in /home3/zc1/public_html/sites/all/themes/mytheme/comment.tpl.php on line 12

Now, I know this error normally indicates a duplicate of the function. But in this case it seems to indicate that the duplication is in the same comment.tpl.php file. And I can't see it.

Here is the file, with the added code included:

&lt;?php ?&gt;
&lt;div class="&lt;?php print $classes . ' ' . $zebra; ?&gt;"&lt;?php print $attributes; ?&gt;&gt;

&lt;?php
  function MYTHEME_preprocess_user_picture(&amp;$variables) { 
$variables['user_picture'] = theme('image_style', array('style_name' =&gt; 'thumbnail_scale_n_crop_120_x_120', 'path' =&gt; $filepath, 'alt' =&gt; $alt, 'title' =&gt; $alt));
} ?&gt;
&lt;?php print $picture ?&gt; 
&lt;span class="submitted"&gt;&lt;?php print $submitted ?&gt;&lt;/span&gt;
   &lt;span class="signature"&gt;
  &lt;?php print $signature ?&gt;
&lt;/span&gt;
&lt;div class="content"&lt;?php print $content_attributes; ?&gt;&gt;
&lt;?php if ($new): ?&gt;
  &lt;span class="new"&gt;&lt;?php print drupal_ucfirst($new) ?&gt;&lt;/span&gt;
&lt;?php endif; ?&gt;
    &lt;?php hide($content['links']); print render($content); ?&gt;
&lt;?php if ($signature): ?&gt;
&lt;?php endif; ?&gt;
  &lt;/div&gt;

&lt;?php print render($content['links']) ?&gt;
&lt;/div&gt;


Any idea what's going on?

This is Drupal 7 and I use Bartik.

Any and all help is greatly appreciated. Thank you. :)
Change function signature with 'function bartik_preprocess_user_picture(&amp;$variables)' and put this function in template.php. Don't forget to clear the cache.