code: def pick(self, req_authn_context=None):
          
  
          if req_authn_context is None:
              return self._pick_by_class_ref(UNSPECIFIED, "minimum")
          if req_authn_context.authn_context_class_ref:
              if req_authn_context.comparison:
                  _cmp = req_authn_context.comparison
              else:
                  _cmp = "exact"
              if _cmp == 'exact':
                  res = []
                  for cls_ref in req_authn_context.authn_context_class_ref:
                      res += (self._pick_by_class_ref(cls_ref.text, _cmp))
                  return res
              else:
                  return self._pick_by_class_ref(
                      req_authn_context.authn_context_class_ref[0].text, _cmp)
          elif req_authn_context.authn_context_decl_ref:
              if req_authn_context.comparison:
                  _cmp = req_authn_context.comparison
              else:
                  _cmp = "exact"
              return self._pick_by_class_ref(
                  req_authn_context.authn_context_decl_ref, _cmp)
docs: Given the authentication context find zero or more places where
          the user could be sent next. Ordered according to security level.
  
          :param req_authn_context: The requested context as an
              RequestedAuthnContext instance
          :return: An URL