def METHOD_NAME(self, request: HttpRequest, application_slug: str) -> HttpResponse:
    """Verify the SAML Request, and if valid initiate the FlowPlanner for the application"""
    # Call the method handler, which checks the SAML
    # Request and returns a HTTP Response on error
    method_response = self.check_saml_request()
    if method_response:
        return method_response
    # Regardless, we start the planner and return to it
    planner = FlowPlanner(self.provider.authorization_flow)
    planner.allow_empty_flows = True
    try:
        plan = planner.plan(
            request,
            {
                PLAN_CONTEXT_SSO: True,
                PLAN_CONTEXT_APPLICATION: self.application,
                PLAN_CONTEXT_CONSENT_HEADER: _("You're about to sign into %(application)s.")
                % {"application": self.application.name},
                PLAN_CONTEXT_CONSENT_PERMISSIONS: [],
            },
        )
    except FlowNonApplicableException:
        raise Http404
    plan.append_stage(in_memory_stage(SAMLFlowFinalView))
    request.session[SESSION_KEY_PLAN] = plan
    return redirect_with_qs(
        "authentik_core:if-flow",
        request.GET,
        flow_slug=self.provider.authorization_flow.slug,
    )