Always ommit trailing php close tags, indent correctly, and remove the IDE unfriendly shorthand

shortcode.php

<?php
if ( ! function_exists( 'shortcode_exists' ) ) {
	/**
	 * Check if a shortcode is registered in WordPress.
	 *
	 * Examples: shortcode_exists( 'caption' ) - will return true.
	 *           shortcode_exists( 'blah' )    - will return false.
	 */
	function shortcode_exists( $shortcode = false ) {
		global $shortcode_tags;

		if ( ! $shortcode )
		return false;

		if ( array_key_exists( $shortcode, $shortcode_tags ) )
			return true;

		return false;
	}
}