code: def prepare_for_authenticate(
              self, entityid=None, relay_state="",
              binding=saml2.BINDING_HTTP_REDIRECT, vorg="", nameid_format=None,
              scoping=None, consent=None, extensions=None, sign=None,
              response_binding=saml2.BINDING_HTTP_POST, **kwargs):
          
  
          reqid, negotiated_binding, info = \
              self.prepare_for_negotiated_authenticate(
                  entityid=entityid,
                  relay_state=relay_state,
                  binding=binding,
                  vorg=vorg,
                  nameid_format=nameid_format,
                  scoping=scoping,
                  consent=consent,
                  extensions=extensions,
                  sign=sign,
                  response_binding=response_binding,
                  **kwargs)
  
          assert negotiated_binding == binding
  
          return reqid, info
docs: Makes all necessary preparations for an authentication request.
  
          :param entityid: The entity ID of the IdP to send the request to
          :param relay_state: To where the user should be returned after
              successfull log in.
          :param binding: Which binding to use for sending the request
          :param vorg: The entity_id of the virtual organization I'm a member of
          :param nameid_format:
          :param scoping: For which IdPs this query are aimed.
          :param consent: Whether the principal have given her consent
          :param extensions: Possible extensions
          :param sign: Whether the request should be signed or not.
          :param response_binding: Which binding to use for receiving the response
          :param kwargs: Extra key word arguments
          :return: session id and AuthnRequest info