How to use the onelogin.saml2.xml_utils.OneLogin_Saml2_XML function in onelogin

:param xml: Encrypted Assertion
        :type xml: Element
        :returns: Decrypted Assertion
        :rtype: Element
        """
        key = self.__settings.get_sp_key()
        debug = self.__settings.is_debug_active()

        if not key:
            raise Exception('No private key available, check settings')

        encrypted_assertion_nodes = OneLogin_Saml2_XML.query(xml, '/samlp:Response/saml:EncryptedAssertion')
        if encrypted_assertion_nodes:
            encrypted_data_nodes = OneLogin_Saml2_XML.query(encrypted_assertion_nodes[0], '//saml:EncryptedAssertion/xenc:EncryptedData')
            if encrypted_data_nodes:
                keyinfo = OneLogin_Saml2_XML.query(encrypted_assertion_nodes[0], '//saml:EncryptedAssertion/xenc:EncryptedData/ds:KeyInfo')
                if not keyinfo:
                    raise Exception('No KeyInfo present, invalid Assertion')
                keyinfo = keyinfo[0]
                children = keyinfo.getchildren()
                if not children:
                    raise Exception('No child to KeyInfo, invalid Assertion')
                for child in children:
                    if 'RetrievalMethod' in child.tag:
                        if child.attrib['Type'] != 'http://www.w3.org/2001/04/xmlenc#EncryptedKey':
                            raise Exception('Unsupported Retrieval Method found')
                        uri = child.attrib['URI']
                        if not uri.startswith('#'):
                            break
                        uri = uri.split('#')[1]
                        encrypted_key = OneLogin_Saml2_XML.query(encrypted_assertion_nodes[0], './xenc:EncryptedKey[@Id="' + uri + '"]')
                        if encrypted_key:

dom = OneLogin_Saml2_XML.to_etree(idp_metadata)
        entity_descriptor_nodes = OneLogin_Saml2_XML.query(dom, '//md:EntityDescriptor')

        idp_entity_id = want_authn_requests_signed = idp_name_id_format = idp_sso_url = idp_slo_url = idp_x509_cert = None

        if len(entity_descriptor_nodes) > 0:
            for entity_descriptor_node in entity_descriptor_nodes:
                idp_descriptor_nodes = OneLogin_Saml2_XML.query(entity_descriptor_node, './md:IDPSSODescriptor')
                if len(idp_descriptor_nodes) > 0:
                    idp_descriptor_node = idp_descriptor_nodes[0]

                    idp_entity_id = entity_descriptor_node.get('entityID', None)

                    want_authn_requests_signed = entity_descriptor_node.get('WantAuthnRequestsSigned', None)

                    name_id_format_nodes = OneLogin_Saml2_XML.query(idp_descriptor_node, './md:NameIDFormat')
                    if len(name_id_format_nodes) > 0:
                        idp_name_id_format = name_id_format_nodes[0].text

                    sso_nodes = OneLogin_Saml2_XML.query(
                        idp_descriptor_node,
                        "./md:SingleSignOnService[@Binding='%s']" % required_sso_binding
                    )

                    if len(sso_nodes) > 0:
                        idp_sso_url = sso_nodes[0].get('Location', None)

                    slo_nodes = OneLogin_Saml2_XML.query(
                        idp_descriptor_node,
                        "./md:SingleLogoutService[@Binding='%s']" % required_slo_binding
                    )

:type idp_metadata: string

        :param required_sso_binding: Parse only POST or REDIRECT SSO endpoints.
        :type required_sso_binding: one of OneLogin_Saml2_Constants.BINDING_HTTP_REDIRECT
            or OneLogin_Saml2_Constants.BINDING_HTTP_POST

        :param required_slo_binding: Parse only POST or REDIRECT SLO endpoints.
        :type required_slo_binding: one of OneLogin_Saml2_Constants.BINDING_HTTP_REDIRECT
            or OneLogin_Saml2_Constants.BINDING_HTTP_POST

        :returns: settings dict with extracted data
        :rtype: dict
        """
        data = {}

        dom = OneLogin_Saml2_XML.to_etree(idp_metadata)
        entity_descriptor_nodes = OneLogin_Saml2_XML.query(dom, '//md:EntityDescriptor')

        idp_entity_id = want_authn_requests_signed = idp_name_id_format = idp_sso_url = idp_slo_url = idp_x509_cert = None

        if len(entity_descriptor_nodes) > 0:
            for entity_descriptor_node in entity_descriptor_nodes:
                idp_descriptor_nodes = OneLogin_Saml2_XML.query(entity_descriptor_node, './md:IDPSSODescriptor')
                if len(idp_descriptor_nodes) > 0:
                    idp_descriptor_node = idp_descriptor_nodes[0]

                    idp_entity_id = entity_descriptor_node.get('entityID', None)

                    want_authn_requests_signed = entity_descriptor_node.get('WantAuthnRequestsSigned', None)

                    name_id_format_nodes = OneLogin_Saml2_XML.query(idp_descriptor_node, './md:NameIDFormat')
                    if len(name_id_format_nodes) > 0:

def get_id(request):
        """
        Returns the ID of the Logout Request
        :param request: Logout Request Message
        :type request: string|DOMDocument
        :return: string ID
        :rtype: str object
        """

        elem = OneLogin_Saml2_XML.to_etree(request)
        return elem.get('ID', None)

def __init__(self, settings, response):
        """
        Constructs the response object.

        :param settings: The setting info
        :type settings: OneLogin_Saml2_Setting object

        :param response: The base64 encoded, XML string containing the samlp:Response
        :type response: string
        """
        self.__settings = settings
        self.__error = None
        self.response = OneLogin_Saml2_Utils.b64decode(response)
        self.document = OneLogin_Saml2_XML.to_etree(self.response)
        self.decrypted_document = None
        self.encrypted = None

        # Quick check for the presence of EncryptedAssertion
        encrypted_assertion_nodes = self.__query('/samlp:Response/saml:EncryptedAssertion')
        if encrypted_assertion_nodes:
            decrypted_document = deepcopy(self.document)
            self.encrypted = True
            self.decrypted_document = self.__decrypt_assertion(decrypted_document)

def get_metadata(url):
        """
        Get the metadata XML from the provided URL
        :param url: Url where the XML of the Identity Provider Metadata is published.
        :type url: string
        :returns: metadata XML
        :rtype: string
        """
        valid = False
        response = urllib2.urlopen(url)
        xml = response.read()

        if xml:
            try:
                dom = OneLogin_Saml2_XML.to_etree(xml)
                idp_descriptor_nodes = OneLogin_Saml2_XML.query(dom, '//md:IDPSSODescriptor')
                if idp_descriptor_nodes:
                    valid = True
            except:
                pass

        if not valid:
            raise Exception('Not valid IdP XML found from URL: %s' % (url))

        return xml

def is_valid(self, request_data, request_id=None):
        """
        Determines if the SAML LogoutResponse is valid
        :param request_id: The ID of the LogoutRequest sent by this SP to the IdP
        :type request_id: string
        :return: Returns if the SAML LogoutResponse is or not valid
        :rtype: boolean
        """
        self.__error = None
        try:
            idp_data = self.__settings.get_idp_data()
            idp_entity_id = idp_data['entityId']
            get_data = request_data['get_data']

            if self.__settings.is_strict():
                res = OneLogin_Saml2_XML.validate_xml(self.document, 'saml-schema-protocol-2.0.xsd', self.__settings.is_debug_active())
                if isinstance(res, str):
                    raise Exception('Invalid SAML Logout Request. Not match the saml-schema-protocol-2.0.xsd')

                security = self.__settings.get_security_data()

                # Check if the InResponseTo of the Logout Response matchs the ID of the Logout Request (requestId) if provided
                in_response_to = self.document.get('InResponseTo', None)
                if request_id is not None and in_response_to and in_response_to != request_id:
                    raise Exception('The InResponseTo of the Logout Response: %s, does not match the ID of the Logout request sent by the SP: %s' % (in_response_to, request_id))

                # Check issuer
                issuer = self.get_issuer()
                if issuer is not None and issuer != idp_entity_id:
                    raise Exception('Invalid issuer in the Logout Request')

                current_url = OneLogin_Saml2_Utils.get_self_url_no_query(request_data)

:type: string

        :param cert: IdP Public Cert to encrypt the nameID
        :type: string

        :param debug: Activate the xmlsec debug
        :type: bool

        :returns: DOMElement | XMLSec nameID
        :rtype: string

        :param nq: IDP Name Qualifier
        :type: string
        """

        root = OneLogin_Saml2_XML.make_root("{%s}container" % OneLogin_Saml2_Constants.NS_SAML)
        name_id = OneLogin_Saml2_XML.make_child(root, '{%s}NameID' % OneLogin_Saml2_Constants.NS_SAML)
        if sp_nq is not None:
            name_id.set('SPNameQualifier', sp_nq)
        name_id.set('Format', sp_format)
        if nq is not None:
            name_id.set('NameQualifier', nq)
        name_id.text = value

        if cert is not None:
            xmlsec.enable_debug_trace(debug)

            # Load the public cert
            manager = xmlsec.KeysManager()
            manager.add_key(xmlsec.Key.from_memory(cert, xmlsec.KeyFormat.CERT_PEM, None))

            # Prepare for encryption

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')
        return (len(encrypted_assertion_nodes) + len(assertion_nodes)) == 1

def get_issuer(request):
        """
        Gets the Issuer of the Logout Request Message
        :param request: Logout Request Message
        :type request: string|DOMDocument
        :return: The Issuer
        :rtype: string
        """

        elem = OneLogin_Saml2_XML.to_etree(request)
        issuer = None
        issuer_nodes = OneLogin_Saml2_XML.query(elem, '/samlp:LogoutRequest/saml:Issuer')
        if len(issuer_nodes) == 1:
            issuer = issuer_nodes[0].text
        return issuer