code: def fetch_captcha_store(self, name, value, attrs=None, generator=None):
          
          try:
              reverse('captcha-image', args=('dummy',))
          except NoReverseMatch:
              raise ImproperlyConfigured('Make sure you\'ve included captcha.urls as explained in the INSTALLATION section on http://readthedocs.org/docs/django-simple-captcha/en/latest/usage.html#installation')
  
          if settings.CAPTCHA_GET_FROM_POOL:
              key = CaptchaStore.pick()
          else:
              key = CaptchaStore.generate_key(generator)
  
          # these can be used by format_output and render
          self._value = [key, u('')]
          self._key = key
          self.id_ = self.build_attrs(attrs).get('id', None)
docs: Fetches a new CaptchaStore
          This has to be called inside render