code: def _authn_context_decl(decl, authn_auth=None):
      
      return factory(saml.AuthnContext,
                     authn_context_decl=decl,
                     authenticating_authority=factory(
                         saml.AuthenticatingAuthority, text=authn_auth))
docs: Construct the authn context with a authn context declaration
      :param decl: The authn context declaration
      :param authn_auth: Authenticating Authority
      :return: An AuthnContext instance