<?php declare (strict_types = 1);

abstract class FOO {
    public array $d = ['a', 'b'];
    public   string $a = 'b';
    public static   float   $b = 0.0;
    public   static   array $c = ['a','b'];
    public ?  float   $e;
    public static ?  float   $f;
    abstract protected function zim();
    final public   static function bar()
    {
        $a = array();
        $b = $_GET['user'] ?? 'nobody';
        $c = isset($_GET['user']) ? $_GET['user'] : 'nobody';
    }
}

class Cache extends BaseConfig
{

}

class Cache extends BaseConfig   implements B
{

}