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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 export_action_form_factory(formats):
 """ Returns an ActionForm subclass containing a ChoiceField populated with the given formats. """

    class _ExportActionForm(ActionForm):
        """
        Action form with export format ChoiceField.
        """
        file_format = forms.ChoiceField(
            label=_('Format'), choices=formats, required=False)
    _ExportActionForm.__name__ = str('ExportActionForm')

    return _ExportActionForm