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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_fields(self):
 """ When static declaration is used, event type choices are fetched too early - even before all apps are initialized. As a result, some event types are missing. When dynamic declaration is used, all valid event types are available as choices. """

        fields = super(BaseHookSerializer, self).get_fields()
        fields['event_types'] = serializers.MultipleChoiceField(
            choices=loggers.get_valid_events(), required=False)
        fields['event_groups'] = serializers.MultipleChoiceField(
            choices=loggers.get_event_groups_keys(), required=False)
        return fields