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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_attachment_types(self):
 """Returns a list of available attachment types """

        bika_setup_catalog = api.get_tool("bika_setup_catalog")
        attachment_types = bika_setup_catalog(portal_type='AttachmentType',
                                              is_active=True,
                                              sort_on="sortable_title",
                                              sort_order="ascending")
        return attachment_types