docs: def lookup(self,istring):
      """
      istring = the ilwd:char string corresponding to a unique id
      """
      try:
        return self.uqids[istring]
      except KeyError:
        curs = self.curs
        curs.execute('VALUES BLOB(GENERATE_UNIQUE())')
        self.uqids[istring] = curs.fetchone()[0]
        return self.uqids[istring]