bbp_get_topics_per_page( int $default = 15 )

function bbp_get_topics_per_page( $default = 15 ) {

	// Get database option and cast as integer
	$retval = get_option( '_bbp_topics_per_page', $default );

	// If return val is empty, set it to default
	if ( empty( $retval ) )
		$retval = $default;

	// Filter and return
	return (int) apply_filters( 'bbp_get_topics_per_page', $retval, $default );
}