bbPress custom bbp_list_forums

gistfile1.aw

<?php
// Custom bbp_list_forums bbPress code by @Lynq 
// Demo: http://teamoverpowered.com/forums/
// Code Discussion: http://bbpress.org/forums/topic/customising-bbp_list_forums-last-poster-block/

public function custom_bbp_list_forums( $args = '' ) {

		// Define used variables
		$output = $sub_forums = $topic_count = $reply_count = $counts = '';
		$i = 0;
		$count = array();

		// Defaults and arguments
		$defaults = array (
			'before'            => '<ul class="bbp-forums-list">',
			'after'             => '</ul>',
			'link_before'       => '<li class="bbp-forum">',
			'link_after'        => '</li>',
			'count_before'      => ' (',
			'count_after'       => ')',
			'count_sep'         => ', ',
			'separator'         => ', ',
			'forum_id'          => '',
			'show_topic_count'  => true,
			'show_reply_count'  => true,
			'show_freshness_link'  => true,
		);
		$r = bbp_parse_args( $args, $defaults, 'list_forums' );
		extract( $r, EXTR_SKIP );

		// Bail if there are no subforums
		if ( !bbp_get_forum_subforum_count( $forum_id ) )
			return;

		// Loop through forums and create a list
		$sub_forums = bbp_forum_get_subforums( $forum_id );
		if ( !empty( $sub_forums ) ) {

			// Total count (for separator)
			$total_subs = count( $sub_forums );
			foreach ( $sub_forums as $sub_forum ) {
				$i++; // Separator count

				// Get forum details
				$count     = array();
				$show_sep  = $total_subs > $i ? $separator : '';
				$permalink = bbp_get_forum_permalink( $sub_forum->ID );
				$title     = bbp_get_forum_title( $sub_forum->ID );

				// Show topic count
				if ( !empty( $show_topic_count ) && !bbp_is_forum_category( $sub_forum->ID ) ) {
					$count['topic'] = bbp_get_forum_topic_count( $sub_forum->ID );
				}

				// Show reply count
				if ( !empty( $show_reply_count ) && !bbp_is_forum_category( $sub_forum->ID ) ) {
					$count['reply'] = bbp_get_forum_reply_count( $sub_forum->ID );
				}

				// Counts to show
				if ( !empty( $count ) ) {
					$counts = $count_before . implode( $count_sep, $count ) . $count_after;
				}
				
				if ( !empty( $show_freshness_link ) ) {
					$freshness_link = "<div class='freshness-forum-link'>" . BBP_Default::custom_get_last_poster_block( $sub_forum->ID ) . "</div>";
				}

				// Build this sub forums link
				if ($i % 2) { $class = "odd-forum-row"; } else { $class = "even-forum-row"; }
				$output .= "<li class='{$class}'><ul>" . $link_before . '<a href="' . $permalink . '" class="bbp-forum-link">' . $title . '</a>' . $counts . $freshness_link . $link_after . "</ul></li>";
			}

			// Output the list
			echo apply_filters( 'bbp_list_forums', $before . $output . $after, $args );
		}
	}

// Then I call the function like this
BBP_Default::custom_bbp_list_forums( array (
		'before'            => '<ul class="bbp-forums-list">',
		'after'             => '</ul>',
		'link_before'       => '<li class="bbp-forum">',
		'link_after'        => '</li>',
		'count_before'      => '<div class="topic-reply-counts">Topics: ',
		'count_after'       => '</div>',
		'count_sep'         => '<br />Posts: ',
		'separator'         => '<div style="clear:both;"></div>',
		'forum_id'          => '',
		'show_topic_count'  => true,
		'show_reply_count'  => true,
		'show_freshness_link' => true,
	));

where shall i put it ? i mean file name from bbpress plugin?