docs: def post_url(self, url, form):
          """
          Internally used to retrieve the contents of a URL using
          the POST request method.
          The `form` parameter is a mechanize.HTMLForm object
          This method will use a POST request type regardless of the method
          used in the `form`.
          """
          _r = self.br.open(url, form.click_request_data()[1])
  
          # check that we've not been redirected to the login page or an error occured
          if self.br.geturl().startswith(self.AUTH_URL):
              raise AuthRequiredException
          elif self.br.geturl().startswith(self.ERROR_URL):
              raise RequestErrorException
          else:
              return _r.read()