system/HTTP/RedirectResponse.php
public function back(int $code = null, string $method = 'auto')
	{
		$this->ensureSession();

		return $this->redirect(previous_url(), $method, $code);
	}
public function back(int $code = null, string $method = 'auto')
	{
		$this->ensureSession();

		return $this->redirect(previous_url(), $method, $code);
	}
Helper function to return to previous page.

Example:
return redirect()->back();

@param integer|null $code
@param string       $method

@return $this