def __init__(self, siteconfig, *args, **kwargs):
        """Initialize the form."""
        from reviewboard.accounts.backends import get_registered_auth_backends

        super(AuthenticationSettingsForm, self).__init__(siteconfig,
                                                         *args, **kwargs)

        self.auth_backend_forms = {}

        cur_auth_backend = (self['auth_backend'].data or
                            self.fields['auth_backend'].initial)

        if cur_auth_backend is self.CUSTOM_AUTH_ID:
            custom_auth_form = LegacyAuthModuleSettingsForm(siteconfig,
                                                            *args, **kwargs)
        else:
            custom_auth_form = LegacyAuthModuleSettingsForm(siteconfig)

        self.auth_backend_forms[self.CUSTOM_AUTH_ID] = custom_auth_form

        backend_choices = []
        builtin_auth_choice = None

        for backend in get_registered_auth_backends():
            backend_id = backend.backend_id

            try:
                if backend.settings_form:
                    if cur_auth_backend == backend_id:
                        backend_form = backend.settings_form(siteconfig,
                                                             *args, **kwargs)
                    else:
                        backend_form = backend.settings_form(siteconfig)

                    self.auth_backend_forms[backend_id] = backend_form
                    backend_form.load()

                choice = (backend_id, backend.name)

                if backend_id == 'builtin':
                    builtin_auth_choice = choice
                else:
                    backend_choices.append(choice)
            except Exception as e:
                logging.error('Error loading authentication backend %s: %s'
                              % (backend_id, e),
                              exc_info=1)

        backend_choices.sort(key=lambda x: x[1])
        backend_choices.insert(0, builtin_auth_choice)
        backend_choices.append(self.CUSTOM_AUTH_CHOICE)
        self.fields['auth_backend'].choices = backend_choices
dataset/ETHPy150Open reviewboard/reviewboard/reviewboard/admin/forms.py/AuthenticationSettingsForm.__init__/operator `==` -> `is`