src/Container/Container.php
protected function request($argument, ServerRequestInterface $request = null)
    {
        $instanceof = $argument instanceof ServerRequestInterface;

        $instanceof === true && $argument = $request ?: $argument;

        return $argument;
    }
protected function request($argument, ServerRequestInterface $request = null)
    {
        $instanceof = $argument instanceof ServerRequestInterface;

        $instanceof === true && $argument = $request ?: $argument;

        return $argument;
    }
Returns the manipulated ServerRequest (from middleware) to an argument.

@param  mixed                                         $argument
@param  \Psr\Http\Message\ServerRequestInterface|null $request
@return mixed