Get include() contents

gistfile1.php

<?php
/**
 * Get include contents
 *
 * @since 1.0.0
 * @param string $filename
 * @return string|bool
 */
function ja_get_include_contents( $filename ) {
	if ( is_file( $filename ) ) {
		ob_start();
		include( $filename );
		return ob_get_clean();
	}
	return false;
}