docs: def _nextSequence(cls, name=None):
          """Return a new sequence number for insertion in self._sqlTable.
  
          Note that if your sequences are not named
          tablename_primarykey_seq    (ie. for table 'blapp' with primary
          key 'john_id', sequence name blapp_john_id_seq) you must give
          the full sequence name as an optional argument to _nextSequence)
          """
          if not name:
              name = cls._sqlSequence
          if not name:
              # Assume it's tablename_primarykey_seq
              if len(cls._sqlPrimary) <> 1:
                  raise "Could not guess sequence name for multi-primary-key"
              primary = cls._sqlPrimary[0]
              name = '%s_%s_seq' % (cls._sqlTable, primary.replace('.','_'))
              # Don't have . as a tablename or column name! =)
          curs = cls.cursor()
          curs.execute("SELECT nextval('%s')" % name)
          value = curs.fetchone()[0]
          curs.close()
          return value