Verifies that the document only contains a single Assertion (encrypted or not)

        :returns: True if only 1 assertion encrypted or not
        :rtype: bool

def validate_num_assertions(self):
        """
        Verifies that the document only contains a single Assertion (encrypted or not)

        :returns: True if only 1 assertion encrypted or not
        :rtype: bool
        """
        encrypted_assertion_nodes = OneLogin_Saml2_XML.query(self.document, '//saml:EncryptedAssertion')
        assertion_nodes = OneLogin_Saml2_XML.query(self.document, '//saml:Assertion')

        valid = len(encrypted_assertion_nodes) + len(assertion_nodes) == 1

        if (self.encrypted):
            assertion_nodes = OneLogin_Saml2_XML.query(self.decrypted_document, '//saml:Assertion')
            valid = valid and len(assertion_nodes) == 1

        return valid