def get_assertion_id(self):
if not self.validate_num_assertions():<EOL><INDENT>raise OneLogin_Saml2_ValidationError(<EOL>'<STR_LIT>',<EOL>OneLogin_Saml2_ValidationError.WRONG_NUMBER_OF_ASSERTIONS<EOL>)<EOL><DEDENT>return self.__query_assertion('<STR_LIT>')[<NUM_LIT:0>].get('<STR_LIT>', None)<EOL>
:returns: the ID of the assertion in the response
:rtype: string