title: Check if redirect url exists
body: <p>After login user should be redirected to the <code>?next=%s</code> url. I want to check if specified url mapped to an existant view. There is <code>reverse()</code> function for getting url by view, i need v.v.
  So, i need the function that Django executes for url pattern match.</p>
  
  <p>I see, the question is simple, but i could not find the answer in google.</p>