WordPress plugin to show full RSS post content when a specific query string exists

gistfile1.txt

<?php
/*
Plugin Name:  RSS Feed Customizer
Plugin URI:   http://webdevstudios.com
Description:  Show full RSS content entries using a query string ( ex: http://example.com/feed/?display=full )
Version:      1.0
Author:       THE Brad
Author URI:   http://webdevstudios.com
*/

add_filter( 'the_excerpt_rss', 'get_full_post_content' );

function get_full_post_content( $content ) {
	
	if ( isset( $_GET['display'] ) && $_GET['display'] == 'full' ) {
		
		//display the entire post
		echo get_the_content();
		
	}else{
		
		//only display the post excerpt
		$output = get_the_excerpt();
		echo $output;
		
	}
	
}