code: def assign_otu_membership(biomfile):
      
      samples = defaultdict(set)
      _ = biomfile.pa()
      for sid in biomfile.ids():
          for otuid in biomfile.ids("observation"):
              if biomfile.get_value_by_ids(otuid, sid) == 1:
                  samples[sid].add(otuid)
      return samples
docs: Determines the OTUIDs present in each sample.
      :type biomfile: biom.table.Table
      :param biomfile: BIOM table object from the biom-format library.
      :rtype: dict
      :return: Returns a dictionary keyed on Sample ID with sets containing
      the IDs of OTUIDs found in each sample.