code: def getSampleTypes(self, active_only=True):
          
          catalog = api.get_tool("bika_setup_catalog")
          query = {
              "portal_type": "SampleType",
              # N.B. The `sortable_title` index sorts case sensitive. Since there
              #      is no sort key for sample types, it makes more sense to sort
              #      them alphabetically in the selection
              "sort_on": "title",
              "sort_order": "ascending"
          }
          results = catalog(query)
          if active_only:
              results = filter(api.is_active, results)
          sampletypes = map(
              lambda brain: (brain.UID, brain.Title), results)
          return DisplayList(sampletypes)
docs: Return all sampletypes