src/core/Registry.php
public function get(string $key = '')
    {
        if (empty($key)) {
            return $this->store;
        } else {
            return $this->store[$key] ?? null;
        }
    }
public function get(string $key = '')
    {
        if (empty($key)) {
            return $this->store;
        } else {
            return $this->store[$key] ?? null;
        }
    }
It returns the variable value getted by the name from the storage.
@param string $key The variable name.
@return mixed|null.