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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_form(self, request, obj=None, **kwargs):
 """ Add the default alternative dropdown with appropriate choices """

        if obj:
            if obj.alternatives:
                choices = [(alternative, alternative) for alternative in obj.alternatives.keys()]
            else:
                choices = [(conf.CONTROL_GROUP, conf.CONTROL_GROUP)]

            class ExperimentModelForm(forms.ModelForm):
                default_alternative = forms.ChoiceField(choices=choices,
                                                        initial=obj.default_alternative,
                                                        required=False)
            kwargs['form'] = ExperimentModelForm
        return super(ExperimentAdmin, self).get_form(request, obj=obj, **kwargs)