private static function connectToDatabase()
 {
     self::$db = new Database();
 }
<?php

require 'vendor/autoload.php';
$app = new \Slim\App();
$app->group('/v1', function () use($app) {
    // API Endpoint for our postcodes
    $app->get('/postcodes/{postcode}', function ($request, $response, $args) {
        $postcodeData = PostcodeDatabase::getPostcodeData($args['postcode']);
        return $response->write(json_encode($postcodeData))->withHeader('Content-Type', 'application/json');
    });
});
// Run app
$app->run();