code: def clear_preview(self):
          
          try:
              rm = self.my_osid_object._get_provider_manager('REPOSITORY')
          except AttributeError:
              rm = self.my_osid_object_form._get_provider_manager('REPOSITORY')
          try:
              aas = rm.get_asset_admin_session_for_repository(
                  Id(self.my_osid_object._my_map['assignedBankIds'][0]))
          except AttributeError:
              # for update forms
              aas = rm.get_asset_admin_session_for_repository(
                  Id(self.my_osid_object_form._my_map['assignedBankIds'][0]))
          if 'preview' not in self.my_osid_object_form._my_map['fileIds']:
              raise NotFound()
          aas.delete_asset(
              Id(self.my_osid_object_form._my_map['fileIds']['preview']['assetId']))
          del self.my_osid_object_form._my_map['fileIds']['preview']
docs: stub