src/Container.php
public function get($key)
    {
        if (!array_key_exists($key, static::$map)) {
            throw new NotFoundException($key);
        }
        if (static::$map[$key] instanceof ReflectionFunction) {
            static::$map[$key] = static::$map[$key]->invoke($this);
        }
        return static::$map[$key];
    }
public function get($key)
    {
        if (!array_key_exists($key, static::$map)) {
            throw new NotFoundException($key);
        }
        if (static::$map[$key] instanceof ReflectionFunction) {
            static::$map[$key] = static::$map[$key]->invoke($this);
        }
        return static::$map[$key];
    }
Resolve the dependency identified by `$key`. Note `$key` is not type
hinted as it would violate the `Psr\Container\ContainerInterface`.

@param string $key The unique identifier for the dependency.
@return mixed Whatever was stored under $key.
@throws Disclosure\NotFoundException if no such $key was registered.